Voice chat system, information processing apparatus, speech recognition method, keyword data electrode detection method, and program for speech recognition

ABSTRACT

A voice chat system includes a plurality of information processing apparatuses that performs a voice chat while performing speech recognition and a search server connected to the plural information processing apparatuses via a communication network. The search server discloses a search keyword list containing the search keywords searched by the search server to at least one of the plural information processing apparatuses. The at least one information processing apparatus includes a recognition word dictionary generating unit that acquires the search keyword list from the search server to generate a recognition word dictionary containing words for use in the speech recognition, and a speech recognition unit that performs speech recognition on voice data obtained from a dialog of the conversation during the voice chat by referencing a recognition database containing the recognition word dictionary.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention contains subject matter related to Japanese PatentApplication JP 2007-107319 filed in the Japan Patent Office on Apr. 16,2007, Japanese Patent Application JP 2007-107324 filed in the JapanPatent Office on Apr. 16, 2007, Japanese Patent Application JP2007-325274 filed in the Japan Patent Office on Dec. 17, 2007, andJapanese Patent Application JP 2007-325275 filed in the Japan PatentOffice on Dec. 17, 2007, the entire contents of which being incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a voice chat system, an informationprocessing apparatus, a speech recognition method, a keyword detectionmethod, and a program.

2. Description of the Related Art

Speech recognition has been studied for a long time, and it has come tobe able to provide a quite highly accurate recognition rate regardingspeech that is read. However, it is still difficult to provide highperformance in the recognition of natural conversation between humans.

In recent years, earnest research has been performed on a technology forextracting the subject of conversation from speech, which is also knownas a topic detection technology. When employing the topic detectiontechnology, a speech recognition unit that extracts text informationfrom the speech plays an important role.

As a method for extracting keywords from a speech, there are known amethod that extracts keywords from a speech only paying attention to thekeywords and a method that recognizes the entire speech usinglarge-vocabulary speech recognition and then extracts keywords from arecognition result. Specifically, the former method uses a method ofextracting a word sequence, for example, from a phoneme lattice, alattice of phonemes of which the sequence was recognizable. Meanwhile,the latter method uses LVCSR (large-vocabulary continuous speechrecognition). If the number of keywords is great, the latter method isadvantageous because of its computational efficiency. In any of themethods, it is necessary to have linguistic understanding on thevocabularies to be recognized, and this can be solved by usinginformation on the frequency of occurrence of the vocabularies to bedetected.

The speech recognition can be classified into isolated word recognitionthat recognizes a isolated word and continuous word recognition thatrecognizes a word sequence composed of plural words. The continuous wordrecognition uses a language model, “a database storing the likelihood oflinkage between words,” to thereby prevent “a word sequence havingsimilar sound but totally different meaning” from being output as arecognition result.

However, the language model describes only the information of the wordsthat are originally recognizable (hereinafter, referred to as knownwords); therefore, it is difficult to properly recognize words that areregistered later (hereinafter, referred to as registered words). On theother hand, in the case of the isolated word recognition, once words areregistered in a recognition word dictionary, the words are recognizedimmediately after the registering. However, in the case of thecontinuous word recognition, only the registering of words is notsufficient but is necessary to be reflected onto the language model;unfortunately the reflecting onto the language model is generallydifficult.

In this respect, an example of the related art, JP-A NO. 2004-252121discloses a method that classifies registered words into categories suchas “personal name” and “place name,” provides a language modelcorresponding to the categories, and correlates the registered wordswith the categories using the language model, whereby new vocabulariesare recognizable by continuous speech recognition.

Meanwhile, selection of the registered words has large issues. Inparticular, proper nouns are often important keywords becauserecognition of the proper nouns allows providing users with usefulinformation.

In this respect, as an example of the related art, JP-A NO. 2002-216026discloses a method that acquires keywords from the information on theInternet and extracts a keyword from the acquired keywords.

There are however numerous proper nouns; therefore it may be practicallydifficult to register all the words that users will speak for speechrecognition in advance.

SUMMARY OF THE INVENTION

For these reasons, even the method disclosed in JP-A NO. 2002-216026 mayhave difficulties in recognizing with high accuracy a keyword relatedthe latest topics from a dialog of the conversation during a voice chat.

The present invention is contrived in view of the above-mentionedsituations. There is a need for providing new and improved voice chatsystem, information processing apparatus, speech recognition method, andprogram that can recognize with high accuracy a keyword existing in adialog of the conversation during a voice chat with high accuracy withhigh accuracy.

There is also a need for providing new and improved informationprocessing apparatus, keyword detection method, and program that candetect a keyword existing in broadcast information (program information)with high accuracy of the conversation during a voice chat.

According to a viewpoint of the present invention, there is provided avoice chat system, including: a plurality of information processingapparatuses that perform a voice chat while performing speechrecognition; and a search server connected to the plural informationprocessing apparatuses via a communication network, wherein the searchserver discloses a search keyword list containing the search keywordssearched by the search server to at least one of the informationprocessing apparatuses, the at least one information processingapparatus including: a recognition word dictionary generating unit thatacquires the search keyword list from the search server to generate arecognition word dictionary containing words for use in the speechrecognition; a speech recognition unit that performs speech recognitionon voice data obtained from a dialog of the conversation during thevoice chat by referencing a recognition database containing therecognition word dictionary; a voice conversation control unit thatperforms communication control of the voice data with at least oneinformation processing apparatus; and a keyword detection unit thatdetects keywords related to the content of the conversation during thevoice chat from the result of the speech recognition.

According to another viewpoint of the present invention, there isprovided an information processing apparatus acquiring, from a searchserver, a search keyword list containing the search keywords searched bythe search server and performing a voice chat with other informationprocessing apparatus, the apparatus including: a recognition worddictionary generating unit that acquires the search keyword list fromthe search server to generate a recognition word dictionary containingwords for use in the speech recognition; a speech recognition unit thatperforms speech recognition on voice data obtained from a dialog of theconversation during the voice chat by referencing a recognition databasecontaining the recognition word dictionary; a voice conversation controlunit that performs communication control of the voice data with theother information processing apparatus; and a keyword detection unitthat detects keywords related to the content of the conversation duringthe voice chat from the result of the speech recognition.

The recognition word dictionary may include: a fixed word dictionary inwhich predetermined words are pre-registered; and a variable worddictionary in which registered words are updated on an as needed basis,and the recognition word dictionary generating unit may select words tobe registered in the variable word dictionary from the search keywordlist that contains higher-rank search keywords of the search server togenerate the variable word dictionary.

The recognition word dictionary generating unit may determine apreference of a user of the information processing apparatus based onhistory information of the keywords detected by the keyword detectionunit and select the words from the search keyword list based on thepreference.

The recognition word dictionary generating unit may search for the wordsselected from the search keyword list using the search server andacquire a sub-keyword related to the words from a search result obtainedby the search, thereby registering the sub-keyword in the variable worddictionary in a correlated manner with the words.

The recognition word dictionary generating unit may apply a weight tothe respective words selected from the search keyword list based onsearch rank information that is determined by a frequency of the wordsbeing searched by the search server.

The recognition word dictionary generating unit may calculate afrequency of the keywords based on history information of the keywordsdetected by the keyword detection unit and change the weight of thewords registered in the variable word dictionary and corresponding tothe keywords.

According to a still another viewpoint of the present invention, thereis provided an information processing apparatus acquiring, from a searchserver, a search keyword list containing the search keywords searched bythe search server, selecting words from the search keyword list,acquiring, from a recognition word dictionary generating device thatapplies weight information for use in speech recognition to the selectedwords, the words having the weight information applied thereto, andperforming a voice chat with other information processing apparatus, theapparatus including: a speech recognition unit that performs speechrecognition on voice data obtained from a dialog of the conversationduring the voice chat by referencing a recognition database containingthe words acquired from the recognition word dictionary generatingdevice; a voice conversation control unit that performs communicationcontrol of the voice data with the other information processingapparatus; and a keyword detection unit that detects keywords related tothe content of the conversation during the voice chat from the result ofthe speech recognition.

According to a still another viewpoint of the present invention, thereis provided a speech recognition method used in an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server and performing a voice chat with other informationprocessing apparatus, the method including the steps of: acquiring thesearch keyword list from the search server to generate a recognitionword dictionary containing words for used in speech recognition;obtaining voice data from the content of the conversation during thevoice chat; analyzing the voice data based on an acoustic feature of thevoice data and generating word sequence candidates corresponding to thecontent of the conversation; and analyzing the generated word sequencecandidates based on a linguistic concatenation feature between the wordsthat constitute the word sequence by referencing a recognition databasefor use in the speech recognition containing the recognition worddictionary, thereby selecting a most feasible word sequence.

According to a still another viewpoint of the present invention, thereis provided a speech recognition method used in an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server, selecting words from the search keyword list, acquiring,from a recognition word dictionary generating device that applies weightinformation for use in speech recognition to the selected words, thewords having the weight information applied thereto, and performing avoice chat with other information processing apparatus, the methodincluding the steps of: acquiring the words having the weightinformation applied thereto from the recognition word dictionarygenerating device and storing the words in a recognition database foruse in speech recognition; obtaining voice data from the content of theconversation during the voice chat; analyzing the voice data based on anacoustic feature of the voice data and generating word sequencecandidates corresponding to the content of the conversation; andanalyzing the generated word sequence candidates based on a linguisticconcatenation feature between the words that constitute the wordsequence by referencing the recognition database, thereby selecting amost feasible word sequence.

According to a still another viewpoint of the present invention, thereis provided a program for a computer that controls an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server and performing a voice chat with other informationprocessing apparatus, the program allowing the computer to execute: arecognition word dictionary generating function that acquires the searchkeyword list from the search server to generate a recognition worddictionary containing words for use in the speech recognition; a speechrecognition function that performs speech recognition on voice dataobtained from a dialog of the conversation during the voice chat byreferencing a recognition database containing the recognition worddictionary; a voice conversation control function that performscommunication control of the voice data with the other informationprocessing apparatus; and a keyword detection function that detectskeywords related to the content of the conversation during the voicechat from the result of the speech recognition.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may also be provided having recorded therein the computerprogram. The recording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to a still another viewpoint of the present invention, thereis provided a program for a computer that controls an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server, selecting words from the search keyword list, acquiring,from a recognition word dictionary generating device that applies weightinformation for use in speech recognition to the selected words, thewords having the weight information applied thereto, and performing avoice chat with other information processing apparatus, the programallowing the computer to execute: a speech recognition function thatperforms speech recognition on voice data obtained from a dialog of theconversation during the voice chat by referencing a recognition databasecontaining the words acquired from the recognition word dictionarygenerating device; a voice conversation control function that performscommunication control of the voice data with the other informationprocessing apparatus; and a keyword detection function that detectskeywords related to the content of the conversation during the voicechat from the result of the speech recognition.

According to a still another viewpoint of the present invention, thereis provided an information processing apparatus, including: arecognition word dictionary generating unit that acquires, from a searchserver, a search keyword list containing the search keywords searched bythe search server to generate a recognition word dictionary containingwords for use in language recognition; a broadcast text informationreceiving unit that receives broadcast text information transmitted froma broadcasting station; a keyword detection unit that detectspredetermined keywords from the broadcast text information byreferencing the recognition word dictionary; and an external displaydevice connection control unit that performs connection control with anexternal display device and outputs the keywords detected from thebroadcast text information to the external display device.

The broadcast text information receiving unit may acquire receptionchannel information concerning a broadcast channel through which theexternal display device is receiving and the broadcast text informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus. Alternatively, thebroadcast text information receiving unit may acquire reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving, from the external display device connectedto the information processing apparatus, and acquires the broadcast textinformation corresponding to the broadcast channel from the broadcastingstation.

The information processing apparatus may store a reference history ofthe keywords in the external display device, and the external displaydevice connection control unit may notify the search server of a keywordselected by the external display device.

According to a still another viewpoint of the present invention, thereis provided An information processing apparatus, including: arecognition word dictionary generating unit that acquires, from a searchserver, a search keyword list containing the search keywords searched bythe search server to generate a recognition word dictionary containingwords for use in speech recognition; a broadcast audio informationreceiving unit that receives broadcast audio information transmittedfrom a broadcasting station; a speech recognition unit that performsspeech recognition on the broadcast audio information by referencing arecognition database containing the recognition word dictionary; akeyword detection unit that detects predetermined keywords from theresult of the speech recognition on the broadcast audio information; andan external display device connection control unit that performsconnection control with an external display device and outputs thekeywords detected from the broadcast audio information to the externaldisplay device.

The broadcast audio information receiving unit may acquire receptionchannel information concerning a broadcast channel through which theexternal display device is receiving and the broadcast audio informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus. Alternatively, thebroadcast audio information receiving unit may acquire reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving, from the external display device connectedto the information processing apparatus, and acquires the broadcastaudio information corresponding to the broadcast channel from thebroadcasting station.

The information processing apparatus may store a reference history ofthe keywords in the external display device, and the external displaydevice connection control unit may notify the search engine of a keywordselected by the external display device.

According to a still another viewpoint of the present invention, thereis provided a keyword detection method, including the steps of:acquiring, from a search server, a search keyword list containing thesearch keywords searched by the search server to generate a recognitionword dictionary containing words for use in language recognition;receiving broadcast text information transmitted from a broadcastingstation; detecting predetermined keywords from the broadcast textinformation by referencing the recognition word dictionary; andperforming connection control with an external display device andoutputting the keywords detected from the broadcast text information tothe external display device.

According to a still another viewpoint of the present invention, thereis provided a keyword detection method, including the steps of:acquiring, from a search server, a search keyword list containing thesearch keywords searched by the search server to generate a recognitionword dictionary containing words for use in speech recognition;receiving broadcast audio information transmitted from a broadcastingstation; performing speech recognition on the broadcast audioinformation by referencing a recognition database containing therecognition word dictionary; detecting predetermined keywords from theresult of the speech recognition on the broadcast audio information; andperforming connection control with an external display device andoutputting the keywords detected from the broadcast audio information tothe external display device.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a recognitionword dictionary generating function that acquires, from a search server,a search keyword list containing the search keywords searched by thesearch server to generate a recognition word dictionary containing wordsfor use in language recognition; a broadcast text information receivingfunction that receives broadcast text information transmitted from abroadcasting station; a keyword detection function that detectspredetermined keywords from the broadcast text information byreferencing the recognition word dictionary; and an external displaydevice connection control function that performs connection control withan external display device and outputs the keywords detected from thebroadcast text information to the external display device.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a recognitionword dictionary generating function that acquires, from a search server,a search keyword list containing the search keywords searched by thesearch server to generate a recognition word dictionary containing wordsfor use in speech recognition; a broadcast audio information receivingfunction that receives broadcast audio information transmitted from abroadcasting station; a speech recognition function that performs speechrecognition on the broadcast audio information by referencing arecognition database containing the recognition word dictionary; akeyword detection function that detects predetermined keywords from theresult of the speech recognition on the broadcast audio information; andan external display device connection control function that performsconnection control with an external display device and outputs thekeywords detected from the broadcast audio information to the externaldisplay device.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to the embodiments of the present invention described above, arecognition word dictionary for speech recognition is created using adatabase acquired from a search server and the speech recognition isperformed using the recognition word dictionary. Therefore, it ispossible to recognize with high accuracy a keyword existing in a dialogof the conversation during a voice chat with high accuracy with highaccuracy. Moreover, a recognition word dictionary for languagerecognition is created using a database acquired from a search serverand keyword detection is performed using the recognition worddictionary. Therefore, it is possible to detect a keyword existing inbroadcast information (program information) with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram showing a voice chat system accordingto a first embodiment of the present invention;

FIG. 2 is a block diagram for explaining the hardware configuration ofan information processing apparatus according to the first embodiment;

FIG. 3 is a block diagram for explaining the configuration of theinformation processing apparatus according to the first embodiment;

FIG. 4 is a block diagram for explaining the configuration of a speechrecognition unit according to the first embodiment;

FIG. 5 is an explanatory diagram showing a recognition databaseaccording to the first embodiment;

FIG. 6 is an explanatory diagram showing an example of a fixed worddictionary according to the first embodiment;

FIG. 7 is an explanatory diagram showing another example of the fixedword dictionary according to the first embodiment;

FIG. 8 is an explanatory diagram showing an example of a variable worddictionary according to the first embodiment;

FIG. 9 is an explanatory diagram showing an example of a category tableaccording to the first embodiment;

FIG. 10 is an explanatory diagram showing another example of thecategory table according to the first embodiment;

FIG. 11 is an explanatory diagram showing an example of a language modelaccording to the first embodiment;

FIG. 12 is an explanatory diagram showing an example of a phoneme listaccording to the first embodiment;

FIG. 13 is an explanatory diagram showing a Kana-phoneme conversion ruleaccording to the first embodiment;

FIG. 14 is a flowchart for explaining an example of a speech recognitionprocess according to the first embodiment;

FIG. 15 is an explanatory diagram showing an example of a computationformula for a language score according to the first embodiment;

FIG. 16 is an explanatory diagram showing a modified example of a commondictionary according to the first embodiment;

FIG. 17 is an explanatory diagram showing a modified example of a fixedword dictionary according to the first embodiment;

FIG. 18 is an explanatory diagram showing a modified example of thecategory table according to the first embodiment;

FIG. 19 is a block diagram for explaining a recognition word dictionarygenerating unit according to the first embodiment;

FIG. 20 is an explanatory diagram showing a recognition word dictionarygeneration/update process according to the first embodiment;

FIG. 21A is an explanatory diagram showing the configuration of thevoice chat system according to the first embodiment;

FIG. 21B is an explanatory diagram showing a modified example of thevoice chat system according to the first embodiment;

FIG. 22 is an explanatory diagram showing the configuration of a keyworddetection system according to a second embodiment of the presentinvention;

FIG. 23 is a block diagram for explaining the configuration of aninformation processing apparatus according to the second embodiment;

FIG. 24 is a block diagram for explaining the configuration of anexternal display device according to the second embodiment;

FIG. 25 is an explanatory diagram showing an information display screenof the external display device according to the second embodiment;

FIG. 26 is a flowchart for explaining a keyword detection methodaccording to the second embodiment;

FIG. 27 is a block diagram for explaining the configuration of a firstmodified example of the information processing apparatus according tothe second embodiment;

FIG. 28 is a flowchart for explaining a keyword detection methodaccording to the present modified example;

FIG. 29 is an explanatory diagram showing a voice chat system accordingto a third embodiment of the present invention;

FIG. 30 is a block diagram for explaining the hardware configuration ofan information processing apparatus according to the third embodiment;

FIG. 31 is a block diagram for explaining the configuration of theinformation processing apparatus according to the third embodiment;

FIG. 32 is a flowchart for explaining an example of a speech recognitionmethod and a keyword extraction method used by the informationprocessing apparatus according to the third embodiment;

FIG. 33 is a flowchart for explaining a keyword synchronization methodin the voice chat system according to the third embodiment;

FIG. 34 is an explanatory diagram showing an example of searchinformation display by the information processing apparatus according tothe third embodiment;

FIG. 35 is an explanatory diagram showing reference history data ofsearch information according to the third embodiment;

FIG. 36A is a simplified block diagram for explaining a speechrecognition method of the information processing apparatus according tothe third embodiment;

FIG. 36B is a simplified block diagram for explaining a first modifiedexample of the speech recognition method of the information processingapparatus according to the third embodiment;

FIG. 36C is a simplified block diagram for explaining a second modifiedexample of the speech recognition method of the information processingapparatus according to the third embodiment;

FIG. 36D is a simplified block diagram for explaining a third modifiedexample of the speech recognition method of the information processingapparatus according to the third embodiment;

FIG. 37 is an explanatory diagram showing a keyword extraction systemaccording to a fourth embodiment of the present invention;

FIG. 38 is a block diagram for explaining the configuration of aninformation processing apparatus according to the fourth embodiment;

FIG. 39 is a block diagram for explaining the configuration of anexternal display device according to the fourth embodiment;

FIG. 40 is an explanatory diagram showing an information display screenof the external display device according to the fourth embodiment;

FIG. 41 is flowchart for explaining a keyword extraction methodaccording to the fourth embodiment;

FIG. 42 is a block diagram for explaining the configuration of a firstmodified example of the information processing apparatus according tothe fourth embodiment; and

FIG. 43 is a flowchart for explaining a keyword extraction methodaccording to the first modified example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the attached drawings. Note that,in this specification and the attached drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

First Embodiment

Hereinafter, a voice chat system according to a first embodiment of thepresent invention will be described in detail.

FIG. 1 is an explanatory diagram showing a voice chat system accordingto a first embodiment. The voice chat system 10 includes a communicationnetwork 12, a search server 14, and information processing apparatuses20A and 20B (hereinafter, sometimes, collectively referred to asinformation processing apparatus or apparatuses 20).

The communication network 12 is a communication network that connectsthe information processing apparatus 20 and the search server 14 toenable bidirectional or unidirectional communication therebetween. Thecommunication network 12 may be constructed, for example, by a publicnetwork, such as Internet, telephone network, satellite communicationnetwork, or broadcast communication channel, or a private network, suchas WAN (Wide Area Network), LAN (Local Area Network), IP-VPN (InternetProtocol-Virtual Private Network), Ethernet (registered trademark), orwireless LAN. The communication network 12 may be wired or wireless.

The search server 14 is a website that users can search for informationavailable through the Internet using keywords or the like. In thepresent embodiment, the search server 14 may provide a full-text searchservice that allows search of the full text of information in storeusing a keyword; or it may be a directory service that allows search ofinformation classified by categories.

The information processing apparatus 20 performs a chat (a voice chat)by means of voice with another information processing apparatus 20connected thereto via the communication network 12. The informationprocessing apparatus 20 can request the search server 14 connectedthereto via the communication network 12 to perform search ofinformation via the communication network 12. The another informationprocessing apparatus 20 performing the voice chat may be connectedthereto via the communication network 12, as shown in the drawing.Alternatively, the another information processing apparatus 20 may bedirectly connected, not via the communication network 12, to a USB(Universal Serial Bus) port, an IEEE 1394 port such as i.Link, an SCSI(Small Computer System Interface) port, an RS-232C port, and the like.

In the shown example shown in the drawing, the information processingapparatus 20 is a desktop PC; however, in the present embodiment, theinformation processing apparatus 20 may be a notebook PC. In the presentembodiment, the information processing apparatus 20 is not limited tothe example described above but may be constructed, for example, by atelevision set-top checkbox, an information appliance such as a home-usegame machine, a mobile phone, a PDA (Personal Digital Assistant), andthe like as long as it is a device capable of having a function ofcommunicating via a network. Additionally or alternatively, theinformation processing apparatus 20 may be a portable device, such as aportable game machine, a PHS, or a portable video/audio player, which iscarried by a user who leased it.

In FIG. 1, only two information processing apparatuses 20 are connectedto the communication network 12. However, the present embodiment is notlimited to the example, and a plurality of information processingapparatuses 20 may be connected to the communication network 12.

(Hardware Configuration of Information Processing Apparatus 20)

Next, the hardware configuration of the information processing apparatus20 according to the present embodiment will be described briefly withreference to FIG. 2.

FIG. 2 is a block diagram for explaining the hardware configuration ofthe information processing apparatus 20 according to the firstembodiment. The information processing apparatus 20 includes a centralprocessing unit (CPU) 201, a read only memory (ROM) 203, a random accessmemory (RAM) 205, a host bus 207, a bridge 209, an external bus 211, aninterface 213, an input device 215, an output device 217, a storagedevice 219, a drive 221, and a communication device 233.

The CPU 201 functions as an arithmetic processing unit and a controlunit. The CPU 201 controls the overall or a part of the internaloperations in the information processing apparatus 20 in accordance withvarious programs recorded in the ROM 203, the RAM 205, the storagedevice 219, or a removable recording medium 16. The ROM 203 stores theprograms, arithmetic parameters, and so on used by the CPU 201. The RAM205 temporarily stores the programs used in execution of the CPU 201 andthe parameters appropriately varying in the execution of the CPU 201.The CPU 201, the ROM 203, and the RAM 205 are connected to each othervia the host bus 207 including inner bus, such as a CPU bus.

The host bus 207 is connected to the external bus 211, such asPeripheral Component Interconnect (PCI) bus, via the bridge 209.

The input device 215 includes an operation unit, such as a mouse, akeyboard, a touch panel, buttons, switches, and a lever, operated by auser and a voice input unit, such as a microphone and a headset. Theinput device 215 may be a remote control unit (a so-called remotecontroller) that uses an infrared ray or other electronic wave or may bean externally connected device such as a mobile phone or a PDAcorresponding to the operation of the information processing apparatus20. The input device 215 may be an input control circuit that generatesan input signal based on information input by the user using theoperation unit or the voice input unit and outputs the generated inputsignal to the CPU 201. The user of the information processing apparatus20 can operate the input device 215 to input a variety of data to theinformation processing apparatus 20 or to instruct the informationprocessing apparatus 20 to perform processing operations.

The output device 217 may be constructed, for example, by a displayunit, such as a cathode ray tube (CRT) display unit, a liquid crystaldisplay (liquid crystal display) unit, a plasma display panel (PDP)unit, an electro-luminescence (EL) display unit, or a lamp, an audiooutput unit including a speaker and a headphone, and a device such as aprinter, a mobile phone, or a fax machine, which can notify users ofacquired information in a visible or audible manner. The output device217 outputs, for example, a variety of information searched by a searchserver. Specifically, the display unit displays a search result for thevariety of information by the search server as a text or an image.Meanwhile, the audio output unit converts the voice data that is playedback into a voice to output the voice.

The storage device 219 is a data storage device which is an example of astorage unit of the information processing apparatus 20 according to thepresent embodiment. The storage device 219 is constructed, for example,by a magnetic storage unit such as a hard disk drive (HDD), asemiconductor storage device, an optical storage device, amagneto-optical storage device, and the like. The storage device 219stores the programs or a variety of data executed by the CPU 201 and avariety of data acquired from the outside.

The drive 221 is a reader-writer for a storage medium. The drive 221 isincorporated in the information processing apparatus 20 or is externallyattached to the information processing apparatus 20. The drive 221 readsout information recorded in the removable storage medium 16, such as amagnetic disk, an optical disk, a magneto-optical disk, or asemiconductor memory, which is loaded in the drive 221, and outputs thereadout information to the RAM 205. The drive 221 can record informationin the removable storage medium 16, such as a magnetic disk, an opticaldisk, a magneto-optical disk, or a semiconductor memory, which is loadedin the drive 221. The removable recording medium 16 may be, for example,a DVD medium, a HD-DVD medium, a Blu-ray medium, a compact flash (CF), amemory stick, or a secure digital (SD) memory card. The removablerecording medium 16 may be, for example, an electronic device or anintegrated circuit (IC) card having mounted thereon a non-contact typeIC chip.

The communication device 223 is a communication interface constructed bya communication device used for connecting to the communication network12. The communication device 223 may be, for example, a communicationcard for wired or wireless local area network (LAN), Bluetooth orwireless USB (WUSB), a router for optical communication, a router forasymmetric digital subscriber line (ADSL), or a modem for variouscommunication protocols. The communication device 223 transmits andreceives a variety of information to and from the Internet or othercommunication devices while transmitting and receiving informationrelated to a voice chat with another information processing apparatus20. The communication network 12 connected to the communication device223 may be constructed by a network such as the Internet, a home LAN, aninfrared communication, or a satellite communication, which is connectedin a wired or wireless manner.

With the configuration described above, the information processingapparatus 20 can perform a voice chat with another informationprocessing apparatus directly connected to the information processingapparatus 20 or with another information processing apparatus connectedthereto via the communication network 12 while acquiring a variety ofinformation from the search server 14 or the like connected thereto viathe communication network 12. Moreover, the information processingapparatus 20 can take out information stored in the informationprocessing apparatus 20 using the removable recording medium 16.

Hereinabove, an example of the hardware configuration that can realizethe functions of the information processing apparatus 20 according tothe present embodiment has been described. The components describedabove may be constructed using a general-purpose element or may beconstructed by a specialized hardware that is specialized to thefunctions of the respective components. Therefore, the hardwareconfiguration can be appropriately modified in accordance with the levelof technology at the time of practicing the present embodiment. Thehardware configuration described above is merely for illustrationpurposes, and the invention is by no means limited to this. Somecomponents such as the host bus 207, the external bus 211, or theinterface 213 may be omitted depending on the form of use.

(Configuration of Information Processing Apparatus 20)

Next, the configuration of the information processing apparatus 20according to the present embodiment will be described in detail. In thefollowing descriptions, two information processing apparatuses 20performing a voice chat will be referred to as a first informationprocessing apparatus 20A and a second information processing apparatus20B. The first and second information processing apparatuses 20A and 20Bgenerate voice data from the sound of the respective users of theinformation processing apparatuses and transmit the voice data to theother information processing apparatus, which is a counterpart of thevoice chat. FIG. 3 is a block diagram for explaining the configurationof the first information processing apparatus 20A according to the firstembodiment.

In the following descriptions, the term “word” refers to a unit that isconveniently treated as a single word in a speech recognition process.It is not necessarily the same as a linguistic word. For example,

(uttered as tarou kun)” may be treated as one word, or may be treated astwo words in the form of “tarou” and “kun.” Further, a larger unit

(uttered as konnichiwa taroukun)” may be treated as one word.

Additionally, the term “phoneme” refers to a unit that is convenientlytreated as a single unit in an acoustic point of view. It is notnecessarily the same as a phonetic syllable or phoneme. For example, inthe word

(uttered as tou kyou),” the part “tou” may be represented by threephoneme symbols “t/o/u,” or “to:,” which is a prolonged sound of “o.”Further, the part “tou” may be represented by “t/o/o.” In addition, asymbol representing a silence may be adopted. Furthermore, symbols thatclassify the silence as “a silence before an utterance”, “a shortsilence interposed between utterances”, “a silence in an utterance”, and“a silence corresponding to

(uttered as tsu)” may be adopted.

As shown in FIG. 3, the first information processing apparatus 20Aaccording to the present embodiment includes a voice input unit 251, aspeech recognition unit 253, a keyword detection unit 255, a keywordmanagement unit 257, a voice conversation control unit 259, a displayunit 261, a voice output unit 263, a communication unit 265, a memoryunit 267, and a recognition word dictionary generating unit 269.

The voice input unit 251 is an interface that inputs, to the firstinformation processing apparatus 20A, a dialog of the conversationduring a voice chat which is the speech uttered by the user of the firstinformation processing apparatus 20A. The voice input unit 251 isconstructed, for example, by an input device such as a microphone or aheadset, connected to the first information processing apparatus 20A.The speech of the users uttered to the microphone or headset isautomatically input in real time to the first information processingapparatus 20A, converted to a voice signal, which is an electric signal,and transmitted to the speech recognition unit 253 via the voice inputunit 251.

The speech recognition unit 253 is constructed, for example, by CPU, ROMor RAM. The speech recognition unit 253 generates voice data from thespeech of the user, which is autonomously input by the voice input unit251 and transmitted in real time, and transmits the voice data to avoice conversation control unit 259 described later, thereby performingspeech recognition based on the generated voice data. The speechrecognition unit 253 generates, as a result of the speech recognition, aword sequence corresponding to the generated voice data and transmitsthe generated word sequence to a keyword detection unit 255 describedlater. The speech recognition unit 253 may be configured to transmit thegenerated word sequence to a display unit 261 described later. Thedetails of the speech recognition unit 253 will be described later.

The keyword detection unit 255 determines whether or not a keywordmanaged by the keyword management unit 257 exists in the word sequencetransmitted from the speech recognition unit 253 and outputs, as akeyword, the word corresponding to the keyword if the keyword exists. Ifplural keywords exist in one word sequence, the keyword detection unit255 may be configured to detect all the corresponding keywords. Thekeyword detection unit 255 may be configured to transmit the keyworddetected from the word sequence to the display unit 261 described later.

For example, when a recognition result, “The recent structural reform iseviscerated,” is transmitted from the speech recognition unit 253 andwhen a keyword, “structural reform” exists in the keyword managed by thekeyword management unit 257, the keyword detection unit 255 outputs“structural reform” as a keyword.

The keyword management unit 257 manages the keywords to be extractedfrom the word sequence generated by the speech recognition unit 253. Thekeyword management unit 257 stores, in the storage unit 267, searchhistory information that is a history of the user of the firstinformation processing apparatus 20A performing search using the searchserver 14 or chat history information that is a history of the userusing a voice chat system of the present embodiment. The managedkeywords are selected based on a search keyword contained in the historyinformation or the detected keywords. The keywords managed by thekeyword management unit 257 are freely referenced by the keyworddetection unit 255. The keyword management unit 257 may also provide themanaged keywords to the speech recognition unit 253, and the speechrecognition unit 253 may update a resonant cycle database describedlater based on the keywords provided by the keyword management unit 257.

The voice conversation control unit 259 is constructed, for example, byCPU, ROM, and RAM, and controls the voice chat with the secondinformation processing apparatus 20B connected via the communicationnetwork 12. The voice conversation control unit 259 receives the voicedata generated by the speech recognition unit 253 and transmits thevoice data to the second information processing apparatus 20B via thecommunication unit 265. The voice conversation control unit 259 receivesvoice data transmitted from the second information processing apparatus20B via the communication unit 265 and transmits the voice data to thevoice output unit 263. The voice conversation control unit 259 may beconfigured to store, every time the voice chat is performed, the datethe voice chat was performed, an identifier for identifying the voicechat, and an identifier for identifying a counterpart of the voice chatin the memory unit 267 as the chat history information in a correlatedmanner.

The voice conversation control unit 259 may be constructed by aspecialized hardware that is specialized to the voice conversationcontrol and may be provided as an application program such as a voicechat program.

The display unit 261 displays the keywords transmitted from the keyworddetection unit 255 to the user of the first information processingapparatus 20A via a display device such as a display of the firstinformation processing apparatus 20A. The display unit 261 may beconfigured to display the word sequence itself, which is the result ofspeech recognition transmitted from the speech recognition unit 253.

The voice output unit 263 is an interface that receives the voice dataof the speech uttered by the user of the second information processingapparatus 20B and inputs the received voice data to the firstinformation processing apparatus 20A. The voice output unit 263 isconstructed, for example, by a speaker or an earphone which is an outputdevice connected to the first information processing apparatus 20A.

The voice data received via the communication unit 265 from the secondinformation processing apparatus 20B is output to the user of the firstinformation processing apparatus 20A via the voice output unit 263.

The communication unit 265 is a communication device installed in thefirst information processing apparatus 20A, for example. Thecommunication unit 265 relays communication of information via thecommunication network 12 between the first information processingapparatus 20A, specifically, the speech recognition unit 253, thekeyword management unit 257, the voice conversation control unit 259,and the recognition word dictionary generating unit 269, and theexternal device of the first information processing apparatus 20A,specifically the search server 14 or the second information processingapparatus 20B. Moreover, the communication unit 265 can communicateinformation with other information processing apparatus that aredirectly connected to the first information processing apparatus 20A notvia the communication network 12.

The memory unit 267 is a storage device installed in the firstinformation processing apparatus 20A, for example, and stores thereindata such as the keywords detected by the keyword detection unit 255 orthe keyword information managed by the keyword management unit 257.Besides these data, the memory unit 267 can also store therein therecognition result such as the word sequence or the voice data generatedby the speech recognition unit 253 or a variety of databases. The memoryunit 267 may appropriately store therein a variety of parameters thatneed be stored when the first information processing apparatus 20Aperforms a process and progress information of the process. The memoryunit 267 is freely accessible when the speech recognition unit 253, thekeyword detection unit 255, the keyword management unit 257, the voiceconversation control unit 259, the recognition word dictionarygenerating unit 269, or the like performs reading or writing to thememory unit 267.

The recognition word dictionary generating unit 269 acquires a searchkeyword list and the like from the search server 14 and selects onlysuitable keywords from the acquired search keyword list, therebygenerating a recognition word dictionary for use in the speechrecognition. The recognition word dictionary generating unit 269 may notonly select the keywords from the acquired search keyword list but alsoadd attribute information of the keywords or related sub-keywords to theselected keywords or a recognition weight for use in the speechrecognition. The details of the recognition word dictionary generatingunit 269 will be described later.

<Speech Recognition Unit 253>

Next, the speech recognition unit 253 according to the presentembodiment will be described in detail with reference to FIG. 4. FIG. 4is a block diagram for explaining the configuration of the speechrecognition unit 253 according to the first embodiment.

As shown in FIG. 4, the speech recognition unit 253 according to thepresent embodiment includes an AD conversion unit 301, a featureparameter extraction unit 303, a matching unit 305, a common dictionarymemory unit 307, and a recognition database 309.

The AD conversion unit 301 samples and quantizes the voice signal, whichis an analog signal transmitted from the voice input unit 251, andconverts the analog voice signal to voice data, which is a digitalsignal. Upon completion of the conversion to the voice data, the ADconversion unit 301 transmits the generated voice data to the voiceconversation control unit 259 and the feature parameter extraction unit303. The AD conversion unit 301 may store the generated voice data inthe memory unit 267.

The feature parameter extraction unit 303 extracts feature parameterssuch as Mel Frequency Cepstrum Coefficients (MFCC) and time differenceparameter thereof, spectrum, power linear predictive coefficients,cepstrum coefficients, and a line spectrum pair, from each frame of theappropriate voice data generated from the AD conversion unit 301. Uponcompletion of extraction of the feature parameters, the featureparameter extraction unit 303 transmits the extracted feature parametersto a matching unit 305 described later. The feature parameter extractionunit 303 may store, in the memory unit 267, the variety of featureparameters extracted from the voice data.

The matching unit 305 generates, as the result of the speechrecognition, the word sequence that is closest to the speech (that is,the content of the conversation during the voice chat) input to thevoice input unit 251 by appropriately referencing the recognitiondatabase 309 and a common dictionary memory unit 307 based on thevariety of feature parameters transmitted from the feature parameterextraction unit 303. Generation method of the word sequence will bedescribed later. Upon completion of generation of the word sequence, thematching unit 305 transmits the generated word sequence to the keyworddetection unit 255. The matching unit 305 may store the generated wordsequence in the memory unit 267.

The matching unit 305 may perform matching using a Viterbi decoder basedon beam search or a stack decoder base on A* search. Additionally oralternatively, a so-called keyword spotting method may be used in thematching. If “recognition weight” information described later is addedthe variety of word dictionaries referenced by the matching unit 305, aweight may be applied to a language score described later and therecognition result may be ranked by the weighted score.

The common dictionary memory unit 307 stores a common dictionary whichis a dictionary of the words that are typically used in the speechrecognition. In the common dictionary stored in the common dictionarymemory unit 307, all the words registered therein are described in acorrelated manner with pronunciation information and categoryinformation. For example, when a proper noun,

(personal name)” is registered in the common dictionary, the propernoun,

is registered in a correlated manner with pronunciation information(phoneme information), “ichiro,” and a category, “_personal name_.” Thedetails of the common dictionary will be described later.

The recognition database 309 is a database that stores a variety ofmodel or rules used by the matching unit 305 for generation of the wordsequence. The details of the recognition database 309 are describedbelow.

<Recognition Database 309>

Next, the recognition database 309 according to the present embodimentwill be described in detail with reference to FIG. 5. FIG. 5 is anexplanatory diagram showing the recognition database 309 according tothe first embodiment.

As shown in FIG. 5, the recognition database 309 according to thepresent embodiment includes a recognition word dictionary memory unit401, an acoustic model memory unit 403, a language model memory unit405, a phoneme list 407, and Kana-phoneme conversion rule 409.

The recognition word dictionary memory unit 401 stores therein arecognition word dictionary used by the matching unit 305 whengenerating the word sequence. The recognition word dictionary includes afixed word dictionary, a variable word dictionary, and a category table,for example.

In the fixed word dictionary, a variety of information such aspronunciations (phoneme sequence) of the words that are not subjected toregistration and deletion, i.e., the words (hereinafter, referred to asfixed word) established in a system in advance and a model describingthe concatenation relationships of the phonemes are described.

In the variable word dictionary, a variety of information such aspronunciation of the keyword words and a model describing theconcatenation relationships of the phonemes are described. Processessuch as registration and deletion of the keyword word and change of thepronunciation are mainly performed with respect to the words registeredin the fixed word dictionary. The variable word dictionary may not storeany information or data therein.

For example, in the case of detecting keywords related to a baseball,the common dictionary memory unit 307 may register therein words thatare generally used in the daily conversation (for example, wordsdescribed in an ordinary dictionary such as Japanese languagedictionary); the fixed word dictionary in the recognition worddictionary memory unit 401 may register therein words that are generallyused in the field of the baseball, such as “play,” “double play,” “pinchhitter,” or “roaster.” The variable word dictionary in the recognitionword dictionary memory unit 401 may register therein proper nouns, suchas “ichiro,” which vary over time. Since the variable word dictionary isupdated on an as needed basis, it is possible to easily performrecognition including keywords related to the latest topics on thebaseball.

Next, the fixed word dictionary according to the present embodiment willbe described with reference to FIGS. 6 and 7. FIGS. 6 and 7 areexplanatory diagrams showing examples of the fixed word dictionaryaccording to the first embodiment.

In FIG. 6, “Symbol” is a character string for identifying a word and canbe represented, for example, by Japanese Kana notation. Entries of thesame symbols are regarded as the entries of the same words. The languagemodel of the present embodiment is represented by the symbol.“Transcription” represents the notation of words, and the characterstring output as a recognition result is the transcription. “PhonemeSequence” is the pronunciation of words as expressed by the phonemesequence. The fixed word dictionary of the present embodiment describesnot only the symbols of the Kana notation as shown in FIG. 6 but alsothe character string having a mixture of Chinese characters and JapaneseHiragana as shown in FIG. 7.

“<start>” and “<end>” described in FIGS. 6 and 7 are special symbolsthat represent “a silence before an utterance” and “a silence after anutterance,” respectively. Therefore, the special symbols do not have acorresponding notation in the transcription column and are representedas “[ ]” (blank).

Besides the items described in FIGS. 6 and 7, the fixed word dictionaryof the present embodiment may include an “attribute” column thatdescribes parts of speech of the words, such as noun or verb, or a genreof the words and a “recognition weight” column that describes weightinformation of the words used in calculation of a language scoredescribed later.

Next, the variable word dictionary according to the present embodimentwill be described with reference to FIG. 8. FIG. 8 is an explanatorydiagram showing an example of a variable word dictionary according tothe first embodiment.

As shown in FIG. 8, the variable word dictionary of the presentembodiment includes a “Symbol” column and a “Kana pronunciation.” In theexample shown in FIG. 8, two categories, “_personal name_” and “_placename_” are described as “symbol.” In the “_personal name_” category, thepronunciations of two words,

(uttered as ichiro)” and

(uttered as sanitarou),” are described in the Kana pronunciation. In the“_place name_” category, a pronunciation of a word,

(uttered as kitashinagawa),” is described in the Kana pronunciation. Thevariable word dictionary of the present embodiment may describe specificwords as well as the categories as shown in FIG. 8. When the specificwords other than the categories as shown in the drawing are described inthe variable word dictionary, individual words are described in the“symbol” column and the “transcription” or “phoneme sequence”corresponding to the words will be provided in the variable worddictionary.

Similar to the case of the fixed word dictionary, the fixed worddictionary of the present embodiment may include an “attribute” columnthat describes parts of speech of the words, such as noun or verb, or agenre of the words and a “recognition weight” column that describesweight information of the words used in calculation of a language scoredescribed later. Since the words described in the variable worddictionary are mainly the words that vary over time, the value describedin the “recognition weight” column is preferably set higher than the“recognition weight” described in the fixed word dictionary. In thisway, a higher “recognition weight” is set to the words described in thevariable word dictionary. Therefore, in a voice chat in which usersusually converse about the ongoing topics, it is possible to selectspecific keywords or the words related to the specific keywords on apreferential basis. Accordingly, the speech recognition can be performedwith high recognition rate.

The details of the generation and update process of the variable worddictionary according to the present embodiment will be described later.

In the category table, the categories contained in the language modelcontained in the language model memory unit 405 and information aboutthe words contained in the categories are described in a correlatedmanner. The category table may be described in a list form or a tableform. The category table may not store any information or data thereinif the language model does not include any categories.

The categories may be classified into classes based on a semanticattribute (for example, “_personal name_,” “_user name_,” “_placename_,” “_shop name_,” and the like) or classes based on the parts ofspeech (for example, “_noun_,” “_verb_,” “_particle_,” and the like).Hereinafter, a notation, “_ . . . _” refers to a category name.

FIG. 9 shows an example of the category table. In the category table,the kind of categories used in the language model described later andinformation about the words belonging to the category are described. Forexample, when two categories, “_personal name_” and “_place name_” areused in the language model, the two categories, “_personal name_” and“_place name_” are entered in the category table as shown in FIG. 9.When a new category is added to the category table, the word belongingto the newly added category may be represented as a blank, and thebelonging words may be added thereto with the progress of learning oradaptation of the language model. In FIG. 9, the words belonging to thecategories, “_personal name_” and “_place name_” are represented as “[]”; this notation represents that there are no belonging words.

FIG. 10 shows another example of the category table of the recognitionword dictionary memory unit 401, in which information about words areentered. In FIG. 10, the entry on the first row represents that words,

(uttered as ichiro)” and

(uttered as sanitarou),” belong to the category of “_personal name_.”

The acoustic model memory unit 403 stores therein an acoustic model thatrepresents an acoustic feature of individual phonemes of the speech tobe recognized. Here, the acoustic model is a model that represents theacoustic feature of a speech for each pronunciation symbol such as vowelor consonant. The acoustic model is used when collating the voice dataof an input speech with a recognition candidate word while payingattention to the similarity as the sound. As the acoustic model, aHidden Markov Model (HMM), for example, can be used; however, theacoustic model according to the present embodiment is not limited to theHMM.

As the acoustic model stored in the acoustic model memory unit 403, twomodels, one for quiet environment (an acoustic model capable ofproviding high recognition rate under quiet environment) and the otherfor noisy environment (an acoustic model capable of providing favorablerecognition rate under noisy environment) may be provided so that eitherone of the models can be referenced depending on the environment.

The language model memory unit 405 stores therein a language model thatdescribes information (hereinafter, referred to as concatenationinformation) representing how the words registered in each dictionary ofthe common dictionary memory unit 307 and the recognition worddictionary memory unit 401 are concatenated (connected). As adescription method, statistical word concatenation probability (n-gramor class n-gram), generation grammar, finite state automaton (FSA) orthe like may be used.

The language model contained in the language model memory unit 405contains concatenation information of a category of the words classifiedfrom a specific point of view as well as the concatenation informationof the words. For example, when “a category to which the wordsrepresenting personal names belong” is represented as a symbol“_personal name” and “a category to which the words representing foodbelongs” is represented as a symbol “_food_,” the language model alsodescribes the concatenation information of “_personal name” and“_food_”; that is, concatenation between categories and concatenationbetween the category and the words stored in advance in the dictionaryare also described.

Therefore, concatenation information of the words that are not containedin the language model can be acquired. For example, when acquiringconcatenation information between

(uttered as ichiro)” and

(a particle, uttered as wa),” even though the concatenation informationof

(uttered as ichiro)” is not described in the language model, if it ispossible to know that the

(uttered as ichiro)” belongs to a category represented as a symbol“_personal name_,” it is possible to acquire the concatenationinformation between

(uttered as ichiro)” and

(a particle, uttered as wa)” by acquiring the concatenation informationbetween “_personal name_” and

(a particle, uttered as wa).”

<Language Model>

Next, a specific example of the language model according to the presentembodiment will be described with reference to FIG. 11. FIG. 11 is anexplanatory diagram showing an example of the language model accordingto the first embodiment.

In FIG. 11, a statistical language model is used as the language model.The statistical language model is a model that describes theconcatenation information of words using a conditional probability. Inthe language model shown in FIG. 11, a tri-gram that represents aprobability of a succession of three words 1, 2, and 3, that is, theprobability of three concatenations of words is used as the statisticlanguage model.

In FIG. 11, “P(word 3|word 1 word 2)” represents a probability ofoccurrence of “word 3” subsequent to a succession of “word 1” and “word2” among a word sequence. In the example shown in the drawing, theprobability of occurrence of

(uttered as wa)” subsequent to a succession of “<start>” and “_personalname_” is “0.012.” Such a probability may be obtained by analyzing textsthat describe a large quantity of chat dialogs. As the language model,besides the tri-gram, bi-gram (two concatenation probability) oruni-gram (probability of occurrence of a word) may be used according tothe necessity.

In the language model of FIG. 11, grammar is described using thecategories as well as the words. That is, in FIG. 11, the “_personalname_” and the “_place name_” refers to the categories, “_personalname_” and “_place name_”; therefore, by describing the tri-gram usingsuch categories, the words representing a personal name or a place namecan be recognized by the speech recognition unit 253 if the words areregistered in the variable word dictionary.

The phoneme list 407 is a list of phoneme symbols used in therecognition database 309. The phoneme list 407 represents one phoneme(or a corresponding one) as one symbol, as shown in FIG. 12. Forexample, in the phoneme list of FIG. 12, vowel+colon (for example, “a:”)represents a prolonged sound, and “N” represents

(Japanese hirakana, uttered as ng). In addition, “sp,” “silB,” “silE,”and “q” all represent a silence, which respectively represent “a silencein an utterance”, “a silence before an utterance”, “a silence after anutterance”, and “a silence corresponding to

(uttered as tsu).”

The Kana-phoneme conversion rule 409 is a rule for converting a Kanacharacter string to a phoneme sequence. In this way, by storing theKana-phoneme conversation rule 409, the common dictionary memory unit307 or the recognition word dictionary memory unit 401 can store andmaintain therein, as pronunciation information, the Kana characterstring that is independent from the phoneme sequence. The Kana-phonemeconversion rule 409 describes the conversion rule from the Kana notationto the phonemes such as the symbols of phonemes correlated to thenotation or all the possible Kana notations. According to theKana-phoneme conversation rule 409 shown in FIG. 13, for example, a Kanacharacter string,

is converted to a phoneme sequence, “i/ch/i/r/o:.”

Hereinabove, an example of the function of the first informationprocessing apparatus 20A according to the present invention has beendescribed. The components described above may be constructed using ageneral-purpose element or circuit or may be constructed by aspecialized hardware that is specialized to the functions of therespective components. The whole functions of the components may beexecuted by a CPU or the like. Therefore, the hardware configuration canbe appropriately modified in accordance with the level of technology atthe time of practicing the present embodiment.

The configuration of the second information processing apparatus 20B issubstantially the same as the first information processing apparatus20A, and descriptions thereof will be omitted.

(Speech Recognition Process of Speech Recognition Unit 253)

Next, the speech recognition process of the speech recognition unit 253according to the present embodiment will be described with reference toFIG. 14. FIG. 14 is a flowchart for explaining an example of the speechrecognition process according to the first embodiment.

The speech recognition process described later is started when a speechis input to the voice input unit 251 such as a microphone from the userof the first information processing apparatus 20A.

The voice signal generated by the voice input unit 251 is firstconverted by the AD conversion unit 301 to the voice data, which is adigital signal, and transmitted to the feature parameter extraction unit303 (Step S101). At this time, the AD conversion unit 301 may store thegenerated voice data in the memory unit 267. Next, the feature parameterextraction unit 303 having transmitted thereto the voice data extracts afeature amount such as Mel cepstrum from the transmitted voice data(Step S103). In extraction of the feature parameter, a variety ofanalysis methods, for example, cepstrum analysis, linear predictiveanalysis, analysis based on acoustic filter using MFCC coefficient maybe used. The feature parameter extraction unit 303 may store in thememory unit 267 the variety of feature parameters extracted from thevoice data.

Once the feature amount is extracted by the feature parameter extractionunit 303, the matching unit 305 references the common dictionary storedin the common dictionary memory unit 307 or the fixed word dictionaryand the variable word dictionary stored in the recognition worddictionary memory unit 401 in the recognition database 309 and therebygenerates a word sequence by connecting some of the words represented assymbols in the dictionaries (Step S105). Subsequently, the matching unit305 calculates an acoustic score of the generated word sequence based onthe acoustic model stored in the acoustic model memory unit 403 of therecognition database 309 (Step S105). Here, the acoustic store is ascore that represents how closely the word sequence, which is acandidate of the speech recognition result, resembles the input voice interms of sound (from the acoustic point of view). A higher acousticscore means that the generated word sequence is acoustically close tothe input voice.

Once the acoustic score is calculated based on the feature parameters,the matching unit 305 selects a predetermined number of word sequenceshaving higher acoustic score based on the calculated acoustic scores(Step S107). Incidentally, the matching unit 305 may store in the memoryunit 267 the calculated acoustic scores or the selected word sequences.

Upon completion of the acoustic score calculation, the matching unit 305calculates a language score of each word sequence selected in Step S107based on the language model contained in the language model memory unit405 of the recognition database 309 (Step S109). For example, if grammaror finite state automaton is used among a variety of language modelsstored in the language model memory unit 405, when the word sequence isacceptable to the language model, the language score of the wordsequence is “1”; when the word sequence is not acceptable to thelanguage model, the language score of the word sequence is “0.”

When the generated word sequence is acceptable to the language model,the matching unit 305 may leave the word sequence selected in Step S107.Alternatively, when the generated word sequence is acceptable as alanguage but not acceptable to the language model, the matching unit 305may delete the word sequence selected in Step S107.

When the statistical language model such as n-gram or class n-gram isused as the language model, the generation probability of the wordsequence is used as the language score. The detailed method ofcalculating the language score is described in Japanese PatentApplication No. 2001-382579 filed by the present applicant(corresponding to JP-A NO. 2003-186494). Incidentally, the matching unit305 may store the calculated language score in the memory unit 267.

The language model according to the present embodiment calculates thelanguage score using the common dictionary stored in the commondictionary memory unit 307 or the fixed word dictionary and the variableword dictionary stored in the recognition word dictionary memory unit401 in the recognition database 309. Since the proper nouns varying overtime are described in the variable word dictionary in an updated manneron an as needed basis, the words frequently used as a topic during avoice chat can be subjected to the language score calculation.

Upon completion of calculation of the acoustic score and the languagescore, the matching unit 305 integrates the acoustic score calculated inStep S105 and the language score calculated in Step S109 and sorts theword sequences, thereby determining the word sequence having thegreatest integrate score as a recognition result (Step S111).Specifically, the matching unit 305 determines as the recognitionresult, the word sequence that maximizes the product or the logarithmicsum of the acoustic score acquired from the acoustic model and thelanguage score acquired from the language model. When information suchas a recognition weight of words is added to the dictionaries used inthe language model, a language score having the recognition weightinformation incorporated therein may be used.

With this, a word sequence that is most feasible from the acoustic andlinguistic points of view is determined as the recognition result. Oncethe most feasible word sequence is determined as the recognition result,the matching unit 305 transmits the determined recognition result to thekeyword detection unit 255 (Step S113). Incidentally, the matching unit305 may store in the memory unit 267, the word sequence, which is thedetermined recognition result.

In this way, in the speech recognition process according to the presentembodiment, upon calculation of the language score, by referencing thevariable word dictionary that describes vocabularies related to thelatest topics (specific topics) that users are likely to converse onduring a voice chat, it is possible recognize the vocabularies relatedto the latest topics on a preferential basis. Therefore, it is possibleto improve the recognition rate of the latest keywords that is difficultto be recognized in a general speech recognition process or thevocabularies related to the keywords. The information displayed as therecognition result is highly likely to be information on the latesttopics, that is, the information that users are interested. Therefore,even if the displayed information is somehow different from theconversation of the users in the voice chat (that is, even when there isan error in the speech recognition result), the users of the voice chatmay be able to broaden the conversation. With this, the errors in thespeech recognition process may be somehow permitted by the usersperforming the voice chat.

<Calculation Method of Language Score>

Next, a calculation method of the language score according to thepresent embodiment will be described with reference to FIG. 15. FIG. 15is an explanatory diagram showing an example of a computation formulafor the language score according to the first embodiment. FIG. 15 showsthe computation formula of the language score when the matching unit 305selects, a word sequence, “<Start>

(uttered as ichiro)

(uttered as wa)

(uttered as nanji)

(uttered as ni)

(uttered as okita)

(uttered as no)<End>,” in Step S109 of FIG. 14.

A language score, “Score(<Start>

(uttered as ichiro)

(uttered as wa)

(uttered as nanji)

(uttered as ni)

(uttered as okita)

(uttered as no)<End>,” is a generation probability of a word sequence,“<Start>

(uttered as ichiro)

(uttered as wa)

(uttered as nanji)

(uttered as ni)

(uttered as okita)

(uttered as no)<End>,” as shown in Formula (1).

The exact value of the language score, “Score(<Start> ichiro wa nanji niokita no <End>,” is computed by “P(<start>) P(ichiro|<start>)P(wa|<start> ichiro) P(nanji|<start> ichiro) P(ni|<start> ichiro wananji) P(okita|<start> ichiro wa nanji ni) P(no|<start> ichiro wa nanjini okita) P(<end>|<start> ichiro wa nanji ni okita no), as shown inFormula (2). As shown in FIG. 16, since the language model 112 uses thetri-gram, the conditional terms, “<start> ichiro wa,” “<start> ichiro wananji,” “<start> ichiro wa nanji ni,” “<start> ichiro wa nanji niokita,” and “<start> ichiro wa nanji ni okita no,” are approximated byconditional probabilities in which the word sequences are limited to theimmediately preceding two words, i.e., “ichiro wa,” “wa nanji,” “nanjini,” “ni okita,” and “okita no,” respectively (Formula (3)).

The conditional probabilities are obtained by referencing the languagemodel as shown in FIG. 11. However, since the language model does notcontain a symbol “ichiro,” the matching unit 305 recognizes that theword represented by a symbol “ichiro” belongs to the category of“_personal name_” by referencing the category table stored in therecognition word dictionary memory unit 401 in the recognition database309, thereby converting “ichiro” to “_personal name_.”

Specifically, as shown in Formula (4), “P(ichiro|<start>)” is convertedto “P(_personal name|<start>) P(ichiro|_personal name_)” and thenapproximated to “P(_personal name_|<start>)/N.” Here, N is the number ofwords belonging to the category of “_personal name_” in the categorytable.

Specifically, when a probability is described in the form of P(X|Y), ifa word X belongs to a category C, the value of P(C|Y) is first obtainedfrom a language model and the obtained value is multiplied by the valueof P(X|C), which is a generation probability of a word X from a categoryC. Assuming the generation probabilities of the words belonging to thecategory C be the same, if the number of words belonging to the categoryC is N, the value of P(X|C) can be approximated to 1/N.

For example, there is only one word represented by the symbol “ichiro”in the category of “_personal name_,” the value of N is “1.” Therefore,as shown in Formula (5), “P(wa|<start> ichiro)” is equal to“P(wa|<start>_personal name_).” In addition, “P(nanji|ichiro wa)” isequal to “P(nanji|_personal name_wa), as shown in Formula (6).

By using the calculation method of the language score, it is possible tocompute the language score of a word sequence containing a variableword. As a result, variable words can be output as the recognitionresult.

In the example describe above, the common dictionary of the commondictionary memory unit 307 does not contain any information or datatherein at the startup of the system. However, several words may bestored in advance in the common dictionary.

FIG. 16 shows an example of the common dictionary in which a keyword“ichiro” is entered in the category of “_personal name_” at the startupof the system. In the example of FIG. 16, since the Kana pronunciation

is entered in the category of “_personal name_” at the startup of thesystem, the keyword can be detected without needing to register thekeyword.

In the example described above, the words stored in the fixed worddictionary are described in the language model, and the words stored inthe variable word dictionary belong to at least one category. Some ofthe words belonging to the category may be stored in the fixed worddictionary.

FIG. 17 shows an example of the fixed word dictionary, and FIG. 18 showsan example of the category table at the startup. Specifically, in thecategory table of FIG. 16, a category “_personal name_” and a symbol,

of a word belonging to the category “_personal name_” are registered inadvance. In the fixed word dictionary 131 of FIG. 17, a symbol

a transcription

of a word represented by the symbol

and a phoneme sequence “i/ch/i/r/o:” are registered in advance.

In the above case, the speech recognition process is performed such thata word “ichiro” belongs to the category of “_personal name_.” That is,the word “ichiro” is treated as a personal name from the beginning.However, since the word “ichiro” is stored in the fixed word dictionary,it is difficult to be deleted or modified.

In this way, by storing possible words in the fixed word dictionary inadvance, it is possible to recognize keywords without needing toregister them in the dictionary.

(Recognition Word Dictionary Generating Unit 269)

Next, the recognition word dictionary generating unit 269 according tothe present embodiment will be described in detail with reference toFIG. 19. FIG. 19 is a block diagram for explaining the recognition worddictionary generating unit according to the first embodiment.

The recognition word dictionary generating unit 269 according to thepresent embodiment includes, as shown in FIG. 19, a search keyword listacquisition unit 501, a keyword selection unit 503, a sub-keywordacquisition unit 505, and a keyword information adding unit 507.

The search keyword list acquisition unit 501 acquires from the searchserver 14 connected thereto via the communication network 12, ahigher-rank search keyword list that contains higher-rank searchkeywords searched by the search server. The acquired higher-rank searchkeywords may be the overall higher-rank search keywords of the searchserver 14 or may be the higher-rank search keywords in a specific field.The number of higher-rank search keywords acquired is arbitrary.

When the higher-rank search keyword list is acquired from a specificfield, the search keyword list acquisition unit 501 may determine thepreference of the user of the first information processing apparatus 20Aby referencing the history information of the voice chat stored in thememory unit 267 or the history information of the recognized keywords,thereby acquiring only the higher-rank search keywords that conform tothe user's preference. For example, the search keyword list acquisitionunit 501 may transform the history information of the voice chat and thehistory information of the recognized keywords into a form of a topicvector having a predetermined dimension using probabilistic latentsemantic analysis (PLSA) or the like. Similarly, the higher-rank searchkeywords of the search server may be transformed into a form of a topicvector using PLSA or the like. The topic vector based on the historyinformation may be compared with the topic vector based on thehigher-rank search keywords, thereby acquiring the higher-rank searchkeywords having a vector similar to the topic vector generated based onthe history information.

The search keyword list acquisition unit 501 transmits the searchkeyword list acquired from the search server 14 to the keyword selectionunit 503. The search keyword list acquisition unit 501 may store theacquired search keyword list in the memory unit 267.

The keyword selection unit 503 selects keywords from the search keywordlist that the search keyword list acquisition unit 501 has acquired fromthe search server 14 based on the preference of the user of the firstinformation processing apparatus 20A. The selection of the keywords maybe performed as follows. The history information of the keywordsdetected by the keyword detection unit 255 is transformed into a form ofa topic vector having a predetermined dimension using PLSA or the like.Similarly, the acquired keyword list may be transformed into a form of atopic vector using PLSA or the like. The topic vector based on thehistory information may be compared with the topic vector based on theacquired keyword list, thereby selecting the search keywords having avector similar to the topic vector generated based on the historyinformation.

When it is possible to acquire the history information of the voice chator the history information of the recognized keywords from the secondinformation processing apparatus 20B, which is a counterpart of thevoice chat, the selection of the keywords may be performed whileperforming a matching process on the history information acquired fromthe second information processing apparatus 20B and the historyinformation stored in the first information processing apparatus 20A. Inthis case, the matching between the two history information may take theunion, integration, or XOR of the two history information.Alternatively, the matching may be unified to the preference of the userof the first or second information processing apparatus 20A or 20B. Whenrecognition weight information described later is added to the acquiredkeywords, the maximum, minimum or average value of the recognitionweights may be used as new recognition weight information.

The keyword selection unit 503 may delete words that are not suitablefor registration in the variable word dictionary from the search keywordlist that the search keyword list acquisition unit 501 has acquired fromthe search server 14. Here, the words that are not suitable forregistration in the variable word dictionary may include: (i) generalwords; (ii) words that are not appropriate from a common sense of view;and (iii) words that are difficult for speech recognition to recognizesuch as words having only one or two phoneme.

Upon selection of keywords from the search keyword list acquired fromthe search server 14, the keyword selection unit 503 transmits theselected keywords to the sub-keyword acquisition unit 505 and thekeyword information adding unit 507 and stores the selected keywords inthe variable word dictionary stored in the recognition word dictionarymemory unit 401. The keyword selection unit 503 may store the selectedkeywords in the memory unit 267.

The sub-keyword acquisition unit 505 searches for the keywords selectedby the keyword selection unit 503 using the search server 14 to acquiresub-keywords related to the keywords selected by the keyword selectionunit 503. When a keyword is searched by the search server 14, aplurality of documents are obtained as a search result. The sub-keywordacquisition unit 505 acquires sub-keywords from the obtained pluraldocuments using a weighting method such as term frequency-inverteddocument frequency (TFIDF). A method of acquiring sub-words from thesearch result by the search server 14 is not limited to the methoddescribed above but all the known methods may be used. For example, if aword,

(Japanese soccer team member),” is transmitted as a keyword from thekeyword selection unit 503, the sub-keyword acquisition unit 505performs search using the search server 14 with the keyword “Japanesesoccer team member” to acquire a keyword such as

(Osim)” or

(Nakata)” from the documents obtained by the search.

Upon completion of the acquisition of the sub-keywords from the searchserver 14, the sub-keyword acquisition unit 505 stores the acquiredsub-keyword in a correlated manner with the keyword used in the searchin the variable word dictionary stored in the recognition worddictionary memory unit 401. The sub-keyword acquisition unit 505transmits the acquired sub-keyword to the keyword information addingunit 507 described later. Incidentally, the sub-keyword acquisition unit505 may store the acquired sub-keyword in the memory unit 267.

The keyword information adding unit 507 adds keyword informationincluding the recognition weight information used in calculation of thelanguage score and the part of speech or the genre of the keywords tothe keywords selected by the keyword selection unit 503 and store theselected keywords and the keyword information in the variable worddictionary in a correlated manner.

The keyword information may be added to the sub-keyword correlated withthe keywords.

The recognition weight information is information that describes arecognition weight, which is a correction factor (weight factor) used incalculation of the language score; as the recognition weight has agreater value, the correction value of the language score increases, andthus keywords having a greater recognition weight are highly likely tobe adopted as the recognition result. For example, a keyword having arecognition weight of 10 will be speech-recognized with a probabilityten times higher than a keyword (i.e., an unweighted keyword) having arecognition weight of 1.

Regarding the determining of the recognition weight, rank information inthe search keyword list acquired from the search server 14 or frequencyof occurrence of keywords in the output of the speech recognition resultmay be used. Since the search keyword list is a list of search keywordsplaced on the higher rank in the search server 14, ranks may be assignedto the keywords in the descending order of their frequencies ofoccurrence in the search; a predetermined recognition weight isdetermined in order of the rank. Specifically, predeterminedcoefficients are assigned to the keywords in the descending order oftheir frequencies of occurrence in the search, and a normalized keywordfrequency is multiplied with the assigned coefficients, therebyobtaining the recognition weight.

Regarding the determining of the recognition weight, information onwhether or not the user of the first information processing apparatus20A has performed the search of the keywords obtained as the speechrecognition result using the search server 14 or not, or the preferenceof the user of the first information processing apparatus 20A may beused.

The attribute information, which is information on the parts of speechor the genre of the keywords, can be added by using the descriptioncontent in the bulletin board or websites provided on the Internet orusing a morphological analysis tool. Alternatively, an encyclopedia, thewikipedia, or Japanese language dictionary available on the Internet maybe appropriately used.

Regarding the acquisition of the search keyword list and thesub-keyword, and the adding of the keyword information, a thesaurus, anontology database, an encyclopedia, a Japanese language dictionary, or amorphological analysis tool, which is stored in a server connectedthereto via the communication network 12, may be used instead of thesearch server 14. The search server 14 may be used in addition to thethesaurus, the ontology database, the encyclopedia, the Japaneselanguage dictionary, and the morphological analysis tool.

<Recognition Word Dictionary Generation/Update Process>

Next, the operation of the recognition word dictionary generating unitaccording to the present embodiment will be described in detail withreference to FIG. 20. FIG. 20 is an explanatory diagram showing arecognition word dictionary generation/update process according to thefirst embodiment.

First, the search keyword list acquisition unit 501 of the recognitionword dictionary generating unit 269 acquires, from the search server 14,a search keyword list describing the higher-rank search keywords basedon the user's preference. As shown in FIG. 20, in the search keywordlist,

(Japanese soccer team member),

(World Baseball Classic),”

(Oh coach),

(Zico),

(Lylics),” “27,”

(Tiramisu),

(Manza Beach),

(after-hour party),”

(shot),” and

(sexually explicit)” are described. The search keyword list acquisitionunit 501 stores the acquired keywords in the memory unit 267 andtransmits them to the keyword selection unit 503 of the recognition worddictionary generating unit 269.

The keyword selection unit 503 deletes words that are not suitable forregistration by referencing the transmitted search keyword list. In theexample described above, general words such as

(after-hour party),

(shot),

(Lylics),” and “27” and words that are not appropriate from a commonsense of view, such as “

(sexually explicit)” are deleted from the search keyword list. Thekeyword selection unit 503 additionally describes the search keywordlist, from which such words are deleted, in the variable worddictionary. Regarding the additional describing in the variable worddictionary, the keyword selection unit 503 may also add descriptions onitems such as a phoneme sequence or a transcription as well as the itemsshown in FIG. 20.

Subsequently, the sub-keyword acquisition unit 505 acquires suchkeywords additionally described in the variable word dictionary andacquires sub-keywords related to the acquired keywords by using thesearch server 14 or the like. For example, as shown in FIG. 20, as aresult of searching the search server 14 based on a keyword,

(Japanese soccer team member), “sub-keywords,

(Osim),

(Nakata),”

(Maki),” and

(Zico),” are acquired. These sub-keywords are additionally described inthe variable word dictionary in a correlated manner with the keyword,

(Japanese soccer team member).” Similarly, the sub-keywords for otherkeywords may be acquired and additionally described in the variable worddictionary in a correlated manner with them.

Next, the keyword information adding unit 507 assigns predeterminedcoefficients to the search keywords, from which unnecessary words weredeleted, in the descending order of their search ranks in the searchserver 14. For example, the keyword information adding unit 507 assignscoefficients 10, 9, 8, and so on to the keywords in the descending orderof their ranks in the search keyword list and multiplies the assignedcoefficients by a value obtained by dividing the frequency of eachkeyword by a normal expectation value, thereby calculating therecognition weight. The thus-obtained recognition weight may bemultiplied by a sigmoid function, for example. The keyword informationadding unit 507 adds the recognition weight information calculated inthe above-described manner to the respective keywords and additionallydescribes them in the variable word dictionary.

The calculation method of the recognition weight information is merelyfor illustration purposes. The calculation method of the recognitionweight information according to the present embodiment is not limited tothe method described above, and other method other than theabove-described method may be used in calculation of the recognitionweight information.

As shown in FIG. 20, in the fixed word dictionary, words generally usedin the daily conversation, such as

(eat),

(drink),

(hit),

(shot),

(player),” and

(after-hour party),” are registered in advance. The words registered inadvance in the fixed word dictionary are general words as describedabove and are not highly likely to be speech-recognized on apreferential basis; therefore, as the recognition weight information,“1” is registered for the words.

The keyword information adding unit 507 acquires attribute information,such as the part of speech or the genre of the respective words, frominformation obtained using a morphological analysis tool or availablefrom the bulletin board on the search server 14, thereby additionallydescribing them in the variable word dictionary. For example, “noun:sports” is added as the attribute information to the keyword,

(Japanese soccer team member),” shown in FIG. 20.

By performing the above-described processes, the recognition worddictionary generating unit 269 can perform the generation and updateprocess of the variable word dictionary on an as needed basis. When thefirst information processing apparatus 20A of the present embodiment isstarted for the first time, there may be a case in which no informationor data is described in the variable word dictionary. For this reason,the recognition word dictionary generating unit 269 performs thegeneration of the variable word dictionary in accordance with theabove-described method. The update of the variable word dictionary canbe performed in an arbitrary manner. For example, the update of thevariable word dictionary may be performed every predetermined periods ona periodic basis, or may be performed in accordance with an updatecommand from the user of the first information processing apparatus 20A.

Regarding the update of the variable word dictionary, when some wordsrecorded as the sub-keywords are speech-recognized with high frequency,the sub-keywords that are speech-recognized with high frequency may benewly stored in the variable word dictionary as a keyword.

When executing the speech recognition process, the matching unit 305performs the calculation of the language model using the contentdescribed in a variety of word dictionaries based on a statisticallanguage model or a grammar model, stored in the language model memoryunit 405 of the recognition database 309. When calculating the languagescore of the words stored in the variable word dictionary, the matchingunit 305 calculates the language score based on the language model usinga common method and multiplies the calculated language score by therecognition weight added to the keyword, thereby obtaining a languagescore for actual use in the speech recognition. Since recognitionweights 1 or larger are added to the words stored in the variable worddictionary as shown in FIG. 20, the language scores calculated for thewords are relatively greater than those of the words stored in thecommon dictionary or the fixed word dictionary. For this reason, amongthe words stored in the variable word dictionary, specific words thatoften appear in the latest topics are recognized with high probability.

In the method described above, the language score calculated using acommon method is multiplied by a recognition weight; therefore, thelanguage score obtained as a calculation result may be 1 or larger insome case. However, in the speech recognition process, the relativeranks of the respective keywords in terms of the language scores aremore important than the absolute values of the language scores;therefore, the language score may have a value of 1 or larger.

As shown in FIG. 21A, the recognition word dictionary generating unit269 may be provided to both the first and second information processingapparatuses 20A and 20B performing the voice chat. As shown in FIG. 21B,the recognition word dictionary generating unit 269 may not be providedto the first and second information processing apparatuses 20A and 20Bperforming the voice chat but provided in a server 18 that relayscommunication between the first and second information processingapparatuses 20A and 20B. As the server shown in FIG. 21B, when therecognition word dictionary generating unit 269 is provided in theserver 18, the server 18 shown in FIG. 21B functions as a recognitionword dictionary generation device that acquires the search keyword listfrom the search server 14, selects keywords from the acquired searchkeyword list using the above-described method, and adds theabove-described weight information to the selected keywords.

A recognition word dictionary generating unit 183 in the server 18acquires a search keyword list from the search server 14 based on thecontent of the voice conversation acquired from the voice conversationcontrol unit 181 and performs selection of the words and addition of therecognition weight information using the acquired search keyword list inaccordance with the above-described process method, thereby creating avariable word dictionary. Thereafter, the recognition word dictionarygenerating unit 183 in the server 18 transmits the created variable worddictionary to the first and second information processing apparatuses20A and 20B. The information processing apparatuses store thetransmitted variable word dictionary in the respective recognitiondatabases 309; therefore, the variable word dictionary can be used inthe speech recognition process. Incidentally, the first and secondinformation processing apparatuses 20A and 20B may acquire, from theserver 18, a list of words having recognition weight information addedthereto and create a variable word dictionary based on the acquired wordlist.

In the first and second information processing apparatuses 20A and 20Bshown in FIGS. 21A and 21B, only some of the processing units of therespective information processing apparatuses are illustrated. Needlessto say, in addition to the processing units illustrated, processingunits illustrated in FIGS. 3 to 5 are also included in the informationprocessing apparatuses.

According to the voice chat system of the present embodiment describedabove, the database of the search server 14 is used in generation of thedictionary for use in the speech recognition. Therefore, keywords thatoften appear in the latest topics can be used as a linguistic knowledgeof the speech recognition. In addition, words related to the keywords ofthe topic are set to have high occurrence probability using a treasuresor the like; therefore, the speech recognition can be performed usingthe related keywords. With this, in the voice chat system according tothe present embodiment, vocabularies related to the latest topic thatusers are likely to converse about are recognized on a preferentialbasis, thereby improving the recognition rate. The information displayedas the recognition result is highly likely to be information on thelatest topics, that is, the information that users are interested.Therefore, even if the displayed information is somehow different fromthe conversation of the users, it provides an advantage that the usersof the voice chat can broaden the conversation.

Second Embodiment

Hereinafter, a keyword detection system according to a second embodimentof the present invention will be described in detail.

FIG. 22 is an explanatory diagram showing the configuration of a keyworddetection system according to the second embodiment of the presentinvention. As shown in FIG. 22, the keyword detection system 11according to the present embodiment includes a communication network 12,a search server 14, and information processing apparatuses 20A and 20B(hereinafter, sometimes, collectively referred to as informationprocessing apparatus or apparatuses 20). The information processingapparatus 20A is connected to an external display device 70 within ahome network 19. The information processing apparatuses 20A and 20B andthe external display device 70 can receive broadcast informationtransmitted from a broadcasting station 80.

The communication network 12 and the search server 14 have the sameconfiguration and provides substantially the same effect as thecommunication network 12 and the search server 14 according to the firstembodiment, and detailed descriptions thereof will be omitted.

The information processing apparatus 20A performs a chat (a voice chat)by means of voice with another information processing apparatus 20Bconnected thereto via the communication network 12. The informationprocessing apparatuses 20A and 20B can request the search server 14connected thereto via the communication network 12 to performreferencing of a database or search of information via the communicationnetwork 12. The another information processing apparatus 20B performingthe voice chat may be connected to the information processing apparatus20A not via the communication network 12, as shown in the drawing.Alternatively, the another information processing apparatus 20B may bedirectly connected to the information processing apparatus 20A, not viathe communication network 12, to a USB port, an IEEE 1394 port such asi.Link, an SCSI port, an RS-232C port, and the like.

The information processing apparatus 20A is connected to the externaldisplay device 70 described later within the home network 19; thereforea variety of data can be communicated between the information processingapparatus 20A and the external display device 70. The connection betweenthe information processing apparatus 20A and the external display device70 may be performed via a connection port such as HDMI-CEC(high-definition multimedia interface-consumer electronics control). Theinformation processing apparatus 20A can receive a broadcast wavecontaining the broadcast information transmitted from the broadcastingstation 80 described later using a receiving function provided therein.

In the shown example shown in the drawing, the information processingapparatus 20 is a desktop PC; however, in the present embodiment, theinformation processing apparatus 20 may be a notebook PC. In the presentembodiment, the information processing apparatus 20 is not limited tothe example described above but may be constructed, for example, by atelevision set-top checkbox, an information appliance such as a home-usegame machine, a mobile phone, a PDA, and the like as long as it is adevice capable of having a function of communicating via a network.Additionally or alternatively, the information processing apparatus 20may be a portable device, such as a portable game machine, a PHS, or aportable video/audio player, which is carried by a user who leased it.

The external display device 70 is a display unit, such as a CRT displayunit, a liquid crystal display unit, a plasma display panel unit, or anelectro-luminescence (EL) display unit. The external display device 70receives the broadcast wave containing the broadcast informationtransmitted from the broadcasting station 80 described later anddisplays the content of the broadcast information on a display area ofthe display unit. Here, the broadcast information transmitted from thebroadcasting station refers to data such as broadcast text information,broadcast audio information, or video information, provided through aterrestrial digital broadcasting such as a one-segment digitalbroadcasting or a 12-segment digital broadcasting (hereinafter, referredto as full-segment digital broadcasting), a cable broadcasting, or anInternet broadcasting via a network. The broadcast wave containing thebroadcast information refers to a wave of the terrestrial digitalbroadcasting such as the one-segment digital broadcasting or thefull-segment digital broadcasting. The external display device 70 cantransmit the received broadcast information to the informationprocessing apparatus 20 via a connection port such as HDMI-CEC. Theexternal display device 70 can receive a variety of data transmittedfrom the information processing apparatus 20 and display informationcorresponding-to-the-data.

Hereinafter, the second embodiment will be described by way of theexample of the terrestrial digital broadcasting.

The broadcasting station 80 transmits a broadcast wave containingbroadcast information composed of data including: broadcast textinformation, broadcast audio information, and video information. Theexternal display device 70 receives the broadcast wave transmitted fromthe broadcasting station 80 and displays caption information or outputsa sound based on the broadcast text information contained in thebroadcast wave. The information processing apparatus 20 can receive thebroadcast wave transmitted from the broadcasting station 80 to use thecontent of the broadcast wave in a variety of processing.

(Configuration of Information Processing Apparatus 20)

Next, the configuration of the information processing apparatus 20according to the present embodiment will be described in detail. Thehardware configuration of the information processing apparatus 20according to the present embodiment is substantially the same as thehardware configuration according to the first embodiment, and detaileddescriptions thereof will be omitted.

FIG. 23 is a block diagram for explaining the configuration of theinformation processing apparatus 20 according to the second embodiment.As shown in FIG. 23, the information processing apparatus 20 accordingto the present embodiment includes a keyword management unit 257, adisplay unit 261, a communication unit 265, a memory unit 267, arecognition word dictionary generating unit 269, a broadcast textinformation receiving unit 271, a keyword detection unit 273, and anexternal display device connection control unit 275.

The keyword management unit 257 manages the keywords to be extractedfrom the word sequence corresponding to the broadcast text informationreceived by the broadcast text information receiving unit 271 describedlater. The keyword management unit 257 stores, in the storage unit 267,search history information that is a history of the user of theinformation processing apparatus 20 performing search using the searchserver 14 and selects the managed keywords based on a search keywordcontained in the history information or the detected keywords. Thekeywords managed by the keyword management unit 257 are freelyreferenced by the keyword detection unit 273 described later. Thekeyword management unit 257 can provide the managed keywords to therecognition word dictionary generating unit 269 described later, and therecognition word dictionary generating unit 269 can perform generationor update of a recognition word dictionary using the keywords providedby the keyword management unit 257 and the search keyword list acquiredfrom the search server 14.

The display unit 261 displays the keywords transmitted from the keyworddetection unit 273 to the user of the information processing apparatus20 via a display device such as a display of the information processingapparatus 20. The display unit 261 may be configured to display the wordsequence itself corresponding to the broadcast text information receivedby the broadcast text information receiving unit 271.

The communication unit 265 is a communication device installed in theinformation processing apparatus 20. The communication unit 265 relayscommunication of information via the communication network 12 betweenthe information processing apparatus 20, specifically, the keywordmanagement unit 257 and the recognition word dictionary generating unit269, and the external device of the information processing apparatus 20,specifically the search server 14 or another information processingapparatus 20. Moreover, the communication unit 265 can communicateinformation with other information processing apparatus that aredirectly connected to the information processing apparatus 20 not viathe communication network 12.

The memory unit 267 is a storage device installed in the informationprocessing apparatus 20, for example, and stores therein data such asthe keywords detected by the keyword detection unit 273 or the keywordinformation managed by the keyword management unit 257. Besides thesedata, the memory unit 267 can store therein the broadcast textinformation received by the broadcast text information receiving unit271 or a variety of databases. The memory unit 267 may appropriatelystore therein a variety of parameters that need be stored when theinformation processing apparatus 20 performs a process and progressinformation of the process. The memory unit 267 is freely accessiblewhen the keyword management unit 257, the display unit 261, thecommunication unit 265, the recognition word dictionary generating unit269, the broadcast text information receiving unit 271, the keyworddetection unit 273, the external display device connection control unit275, or the like performs reading or writing to the memory unit 267.

The recognition word dictionary generating unit 269 acquires a searchkeyword list from the search server 14 and selects only suitablekeywords from the acquired search keyword list, thereby generating arecognition word dictionary for use in the speech recognition. Therecognition word dictionary generating unit 269 selects the keywordsfrom the acquired search keyword list and may add attribute informationof the keywords or related sub-keywords to the selected keywords or arecognition weight for use in the speech recognition. In addition, therecognition word dictionary generating unit 269 may perform generationor update of the recognition word dictionary using the keywordstransmitted from the keyword management unit 257 or keywords that thekeyword detection unit 273 has detected from the broadcast textinformation received by the broadcast text information receiving unit271 described later. The detailed configuration of the recognition worddictionary generating unit 269 according to the present embodiment orthe generation method of the recognition word dictionary issubstantially the same as the configuration of the recognition worddictionary generating unit 269 or the generation method according to thefirst embodiment, and detailed descriptions thereof will be omitted.

The broadcast text information receiving unit 271 acquires, from theexternal display device 70, reception channel information concerning abroadcast channel through which the external display device 70 iscurrently receiving. Here, the reception channel information refers toinformation that represents a broadcast channel through which theexternal display device 70 is currently receiving. The broadcast textinformation receiving unit 271 can synchronize the reception broadcastchannel of the broadcast text information receiving unit 271 with thereception broadcast channel of the external display device 70 byacquiring the reception channel information from the external displaydevice 70.

The broadcast text information receiving unit 271 receives a broadcastwave corresponding to the reception broadcast channel of the externaldisplay device 70 directly from the broadcasting station 80 based on theacquired reception channel information. At this time, the broadcast textinformation receiving unit 271 may be configured to directly receive anone-segment broadcast wave among the broadcast wave transmitted from thebroadcasting station 80 and acquires text information from the receivedwave. The broadcast text information receiving unit 271 may beconfigured to directly receive the full-segment broadcast wavetransmitted from the broadcasting station 80.

The broadcast text information receiving unit 271 may be configured toreceive the broadcast text information received by the external displaydevice 70 and transmitted to the information processing apparatus 20from the external display device 70 based on the acquired receptionchannel information.

The broadcast text information receiving unit 271 outputs the receivedbroadcast text information to the keyword detection unit 273 describedlater. The broadcast text information receiving unit 271 may record thereceived broadcast text information in the memory unit 267.

The keyword detection unit 273 determines whether or not a keywordmanaged by the keyword management unit 257 exists in the word sequencecorresponding to the broadcast text information transmitted from thebroadcast text information receiving unit 271 and outputs, as a keyword,the word corresponding to the keywords if the keyword exists. If pluralkeywords exist in one word sequence, the keyword detection unit 273 maybe configured to detect all the corresponding keywords. The keyworddetection unit 273 may be configured to transmit the keyword detectedfrom the word sequence to the display unit 261.

For example, when a recognition result, “The recent structural reform iseviscerated” is transmitted from the broadcast text informationreceiving unit 271 and a keyword, “structural reform” exists in thekeyword managed by the keyword management unit 257, the keyworddetection unit 273 outputs “structural reform” as a keyword.

The external display device connection control unit 275 performsconnection control between the information processing apparatus 20 andthe external display device 70 connected to the information processingapparatus 20. The external display device connection control unit 275transmits the keywords or the like detected by the keyword detectionunit 273 to the external display device 70. Upon notified by theexternal display device 70 that the user of the external display device70 has referenced or selected a specific keyword or an article relatedto the keyword, the external display device connection control unit 267may record the reference history or selection history in the memory unit267 and notify the search server 14 via the communication unit 265. Thesearch server 14 can use the reference history or the selection historyin a variety of processing executed within the search server 14.Incidentally, when transmitting data corresponding to a variety ofinformation to the external display device 70, the external displaydevice connection control unit 275 may transform a format of the data tobe transmitted into a format that can be displayed by the externaldisplay device 70.

Hereinabove, an example of the function of the information processingapparatus 20 according to the present embodiment has been described. Thecomponents described above may be constructed using a general-purposeelement or circuit or may be constructed by a specialized hardware thatis specialized to the functions of the respective components. The wholefunctions of the components may be executed by a CPU or the like.Therefore, the hardware configuration can be appropriately modified inaccordance with the level of technology at the time of practicing thepresent embodiment.

The information processing apparatus 20 according to the presentembodiment may further include the speech recognition unit or the voiceconversation control unit of the information processing apparatus 20according to the first embodiment. The information processing apparatus20 may further include a database memory unit that stores the content ofthe search keyword list recorded in the search server 14. With this, thecontent of the search keyword list can be stored in the database memoryunit provided in the information processing apparatus 20. Therefore, itis possible to shorten the time necessary for the information processingapparatus 20 to access the search server 14. In addition, by updatingthe content of the database memory unit on a periodic basis, theinformation processing apparatus 20 can acquire the content of thelatest search keyword list recorded in the search server 14.

(Configuration of External Display Device 70)

Next, the configuration of the external display device 70 according tothe present embodiment will be described in detail with reference toFIGS. 24 and 25. FIG. 24 is a block diagram for explaining theconfiguration of an external display device according to the secondembodiment. FIG. 25 is an explanatory diagram showing an informationdisplay screen of the external display device according to the secondembodiment.

The hardware of the external display device 70 according to the presentembodiment includes a display element such as a CRT, a liquid crystaldisplay panel, a plasma display panel, or an EL panel, and a drivecontrol circuit that is constructed by CPU, ROM, and RAM and used incontrolling the driving of the display element.

As shown in FIG. 24, the external display device 70 of the presentembodiment includes a broadcast receiving unit 701, a connection portcontrol unit 703, a broadcast information display control unit 705, akeyword information display control unit 707, and a display unit 709.

The broadcast receiving unit 701 receives a broadcast wave transmittedfrom the broadcasting station 80 and outputs data such as broadcast textinformation, broadcast audio information, or video information,contained in the broadcast wave to the connection port control unit 703and the broadcast information display control unit 705, which will bedescribed later. The broadcast receiving unit 701 may be configured torecord the received information in a memory unit (not shown) provided inthe external display device 70 or an externally attached memory unit(not shown) connected to the external display device 70.

The connection port control unit 703 controls a connection port such asHDMI-CEC capable of digital communication with the informationprocessing apparatus 20. The connection port control unit 703 transmitsthe reception channel information about the broadcast channel, throughwhich the broadcast receiving unit 701 is receiving, to the informationprocessing apparatus 20 via the connection port such as MDMI-CEC. Thedata received by the broadcast receiving unit 701, such as broadcasttext information, broadcast audio information, and video information,may be output to the information processing apparatus 20 via theconnection port control unit 703. The variety of data transmitted fromthe information processing apparatus 20 are input to the externaldisplay device 70 via the connection port control unit 703. The varietyof data transmitted from the information processing apparatus 20 istransmitted to the keyword information display control unit 707described later.

The broadcast information display control unit 705 performs displaycontrol when displaying the broadcast text information, the broadcastaudio information, and the video information transmitted from thebroadcast receiving unit 701 on the display unit 709 described later.

The keyword information display control unit 707 performs displaycontrol when displaying the keyword information transmitted from theinformation processing apparatus 20 on the display unit 709 describedlater. Here, the keyword information transmitted from the informationprocessing apparatus 20 refers to information that includes the keywordsextracted by the information processing apparatus 20, a search resultfor the extracted keywords, and the articles related to the keywords.Upon receiving, from the display unit 709, a request for acquisition ofdetailed information on the information selected by the user of theexternal display device 70 selecting the information displayed on thedisplay unit 709 by means of an input device such as a mouse, akeyboard, or a remote controller, the keyword information displaycontrol unit 707 transmits the detailed information acquisition requestto the information processing apparatus 20 via the connection portcontrol unit 703.

The display unit 709 displays, on an information display screen of theexternal display device 70, the broadcast text information, thebroadcast audio information, and the video information, which aredisplay-controlled by the broadcast information display control unit705, and the keyword information, which is display-controlled by thekeyword information display control unit 707.

The information display screen 751 of the external display device 70normally includes an image display area 753 on which the broadcast textinformation, the broadcast audio information, and the video informationare displayed. Here, when the keyword information is transmitted fromthe information processing apparatus 20, the display area of theinformation display screen 751 is divided to generate a keywordinformation display area 755 on which the keyword information isdisplayed. The image display area 753 is controlled, for example, by thebroadcast information display control unit 705, and the keywordinformation display are 755 is controlled, for example, by the keywordinformation display control unit 707.

The details of the keyword information display area 755 aresubstantially the same as the search result display screen 50 of theinformation processing apparatus according to the first embodiment ofthe present invention, and detailed descriptions thereof will beomitted.

Hereinabove, an example of the function of the external display device70 according to the present invention has been described. The componentsdescribed above may be constructed using a general-purpose element orcircuit or may be constructed by a specialized hardware that isspecialized to the functions of the respective components. The wholefunctions of the components may be executed by a CPU or the like.Therefore, the hardware configuration can be appropriately modified inaccordance with the level of technology at the time of practicing thepresent embodiment.

(Keyword Detection Method)

Next, an example of a keyword detection method performed by theinformation processing apparatus 20 according to the present embodimentwill be described in detail with reference to FIG. 26. FIG. 26 is aflowchart for explaining a keyword detection method according to thesecond embodiment.

First, the broadcast text information receiving unit 271 of theinformation processing apparatus 20 receives broadcast text informationfrom the external display device 70 or the broadcasting station 80 basedon the reception channel information acquired from the external displaydevice 70, thereby acquiring the character string of the broadcastcaption as text information data (Step S201). The broadcast textinformation receiving unit 271 outputs the acquired text informationdata to the keyword detection unit 273.

Next, the keyword detection unit 273 applies morphological analysis tothe transmitted text information data to extract words from thecharacter string and records the extracted words on a memory of theinformation processing apparatus 20 (Step S203).

Next, the keyword detection unit 273 searches for the extracted wordsusing the content of the keyword management unit 257 (Step S205).

Subsequently, the keyword detection unit 273 determines whether or notthe extracted words exist in the keyword management unit 257 (StepS207). When the extracted words exist in the keyword management unit257, the keyword detection unit 273 records the existing extracted wordson the memory as broadcast keyword data (Step S209). When the extractedwords do not exist in the keyword management unit 257, the keyworddetection unit 273 performs a process of Step S211 described later.

Next, the keyword detection unit 273 determines whether or not theextracted words, which were not found in the keyword management unit257, exist on the memory (Step S211). When the unfound words exist onthe memory, the process of Step S205 is performed. When the unfoundwords do not exist in the memory, the keyword detection unit 273 outputsthe broadcast keyword data existing on the memory as an extractedkeyword (Step S213).

By using the method described above, the information processingapparatus 20 according to the present embodiment can extract keywordsfrom the received broadcast text information.

In the information processing apparatus 20 according to the presentembodiment, the words (keywords) existing in the keyword management unit257 are automatically extracted from the broadcast text informationtransmitted from the broadcasting station. Therefore, it is possible todisplay the extracted keywords to the external display device 70. Byusing such a function, the user performing bidirectional communicationsuch as a chat using the information processing apparatus 20 or theexternal display device 70 can use the extracted keywords as a topic ofthe chat or the like.

First Modified Example of Information Processing Apparatus according toSecond Embodiment

Next, a first modified example of the information processing apparatus20 according to the present embodiment will be described in detail withreference to FIGS. 27 and 28. FIG. 27 is a block diagram for explainingthe configuration of the first modified example of the informationprocessing apparatus 20. FIG. 28 is a flowchart for explaining a keyworddetection method according to the present modified example. The hardwareconfiguration of the information processing apparatus 20 according tothe present modified example is substantially the same as the hardwareconfiguration of the second embodiment of the present invention, anddetailed descriptions thereof will be omitted.

As shown in FIG. 27, the information processing apparatus 20 accordingto the present modified example includes a speech recognition unit 253,a keyword detection unit 255, a keyword management unit 257, a displayunit 261, a communication unit 265, a memory unit 267, a recognitionword dictionary generating unit 269, a broadcast audio informationreceiving unit 277, an external display device connection control unit275.

The keyword management unit 257, the display unit 261, the communicationunit 265, the memory unit 267, and the external display deviceconnection control unit 275 according to the present modified examplehave substantially the same configuration and provides substantially thesame effect as the keyword management unit 257, the display unit 261,the communication unit 265, the memory unit 267, and the externaldisplay device connection control unit 275, and detailed descriptionsthereof will be omitted.

The speech recognition unit 253 performs speech recognition based onbroadcast audio information received by the broadcast audio informationreceiving unit 277 described later. The speech recognition unit 253generates a word sequence corresponding to the broadcast audioinformation as a speech recognition result and transmits the generatedword sequence to the keyword detection unit 255 described later. Thespeech recognition unit 253 may be configured to transmission thegenerated word sequence to the display unit 261. The detailedconfiguration and the speech recognition method of the speechrecognition unit 253 are substantially the same as the configuration andthe speech recognition method of the speech recognition unit 253according to the first embodiment of the present invention, and detaileddescriptions thereof will be omitted.

The keyword detection unit 255 determines whether or not a keywordmanaged by the keyword management unit 257 exists in the word sequencecorresponding to the broadcast audio information transmitted from thespeech recognition unit 253 and outputs, as a keyword, the wordcorresponding to the keyword if the keyword exists. If plural keywordsexist in one word sequence, the keyword detection unit 255 may beconfigured to detect all the corresponding keywords. The keyworddetection unit 255 may be configured to transmit the keyword detectedfrom the word sequence to the display unit 261 described later.

For example, when a recognition result “The recent structural reform iseviscerated” is transmitted from the speech recognition unit 253 andwhen a keyword “structural reform” exists in the keyword managed by thekeyword management unit 257, the keyword detection unit 255 outputs“structural reform” as a keyword.

The recognition word dictionary generating unit 269 acquires a searchkeyword list and the like from the search server 14 and selects onlysuitable keywords from the acquired search keyword list, therebygenerating a recognition word dictionary for use in the speechrecognition. The recognition word dictionary generating unit 269 selectsthe keywords from the acquired search keyword list and may add attributeinformation of the keywords or related sub-keywords to the selectedkeywords or a recognition weight for use in the speech recognition. Inaddition, the recognition word dictionary generating unit 269 mayperform generation or update of the recognition word dictionary usingthe keywords transmitted from the keyword management unit 257 orkeywords that the keyword detection unit 255 has detected from thebroadcast audio information received by the broadcast audio informationreceiving unit 277 described later. The detailed configuration of therecognition word dictionary generating unit 269 according to the presentembodiment or the generation method of the recognition word dictionaryis substantially the same as the configuration of the recognition worddictionary generating unit 269 or the generation method according to thefirst embodiment, and detailed descriptions thereof will be omitted.

The broadcast audio information receiving unit 277 acquires, from theexternal display device 70, reception channel information concerning abroadcast channel through which the external display device is currentlyreceiving. The broadcast audio information receiving unit 277 cansynchronize the reception broadcast channel of the broadcast audioinformation receiving unit 277 with the reception broadcast channel ofthe external display device 70 by acquiring the reception channelinformation from the external display device 70.

The broadcast audio information receiving unit 277 receives a broadcastwave corresponding to the reception broadcast channel of the externaldisplay device 70 directly from the broadcasting station 80 based on theacquired reception channel information. At this time, the broadcastaudio information receiving unit 277 may be configured to directlyreceive an one-segment broadcast wave among the broadcast wavetransmitted from the broadcasting station 80 and acquires audioinformation from the received wave. The broadcast audio informationreceiving unit 277 may be configured to directly receive thefull-segment broadcast wave transmitted from the broadcasting station80.

The broadcast audio information receiving unit 277 may be configured toreceive the broadcast audio information received by the external displaydevice 70 and transmitted to the information processing apparatus 20from the external display device 70 based on the acquired receptionchannel information.

The broadcast audio information receiving unit 277 outputs the receivedbroadcast audio information to the speech recognition unit 253. Thebroadcast audio information receiving unit 277 may record the receivedbroadcast audio information in the memory unit 267.

Hereinabove, an example of the function of the information processingapparatus 20 according to the present modified example has beendescribed. The components described above may be constructed using ageneral-purpose element or circuit or may be constructed by aspecialized hardware that is specialized to the functions of therespective components. The whole functions of the components may beexecuted by a CPU or the like. Therefore, the hardware configuration canbe appropriately modified in accordance with the level of technology atthe time of practicing the present embodiment.

The information processing apparatus 20 according to the presentmodified example may further include the speech recognition unit or thevoice conversation control unit of the information processing apparatus20 according to the first embodiment. The information processingapparatus 20 may further include a database memory unit that stores thecontent of the search keyword list recorded in the search server 14.With this, the content of the search keyword list can be stored in thedatabase memory unit provided in the information processing apparatus20. Therefore, it is possible to shorten the time necessary for theinformation processing apparatus 20 to access the search server 14. Inaddition, by updating the content of the database memory unit on aperiodic basis, the information processing apparatus 20 can acquire thecontent of the latest search keyword list recorded in the search server14.

(Keyword Detection Method)

Next, an example of a keyword detection method performed by theinformation processing apparatus 20 according to the present modifiedexample will be described in detail with reference to FIG. 28.

First, the broadcast audio information receiving unit 277 of theinformation processing apparatus 20 receives broadcast audio informationfrom the external display device 70 or the broadcasting station 80 basedon the reception channel information acquired from the external displaydevice 70, and the speech recognition unit 253 performs speechrecognition on the broadcast audio information to determine a speechrecognition result (Step S301). The speech recognition unit 253 outputsthe determined speech recognition result to the keyword detection unit255.

Next, the keyword detection unit 255 applies morphological analysis tothe speech recognition result to extract words from the speechrecognition result and records the extracted words on a memory of theinformation processing apparatus 20 (Step S303).

Next, the keyword detection unit 255 searches for the extracted wordsusing the content of the keyword management unit 257 (Step S305).

Subsequently, the keyword detection unit 255 determines whether or notthe extracted words exist in the keyword management unit 257 (StepS307). When the extracted words exist in the keyword management unit257, the keyword detection unit 255 records the existing extracted wordson the memory as broadcast keyword data (Step S309). When the extractedwords do not exist in the keyword management unit 257, the keyworddetection unit 255 performs a process of Step S311 described later.

Next, the keyword detection unit 255 determines whether or not theextracted words which were not found in the keyword management unit 257exist on the memory (Step S311). When the unfound words exist on thememory, the process of Step S305 is performed. When the unfound words donot exist in the memory, the keyword detection unit 255 outputs thebroadcast keyword data existing on the memory as an extracted keyword(Step S313).

By using the method described above, the information processingapparatus 20 according to the present modified example can extractkeywords from the received broadcast audio information.

In the information processing apparatus 20 according to the presentmodified example, the words (keywords) existing in the keywordmanagement unit 257 are automatically extracted from the broadcast audioinformation transmitted from the broadcasting station 80. Therefore, itis possible to display the extracted keywords to the external displaydevice 70. By using such a function, the user performing bidirectionalcommunication such as a chat using the information processing apparatus20 or the external display device 70 can use the extracted keywords as atopic of the chat or the like.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the attached claims or the equivalents thereof.

For example, in the embodiments described above, the broadcastingstation 80 transmits a terrestrial digital broadcasting. However, thebroadcasting station 80 may provide a cable broadcasting or an Internetbroadcasting.

In the embodiments described above, FIG. 27 shows the case in which thebroadcasting station 80 provides a television program through aterrestrial digital broadcasting. However, AV contents provided by acamcorder that user can personally capture and reproduce images with.

In the embodiments described above, a variety of word dictionaries foruse in the speech recognition are stored in the common dictionary memoryunit 307 and the recognition word dictionary memory unit 401 in therecognition database 309. However, the variety of word dictionaries usedin the speech recognition may be stored in either one of the memoryunits.

In the embodiments described above, only one fixed word dictionary, onlyone variable word dictionary, and only one category table are stored inthe recognition word dictionary memory unit 401. However, plural fixedword dictionary, plural variable word dictionary, and/or plural categorytable may be stored in the recognition word dictionary memory unit 401.By storing plural fixed word dictionary, plural variable worddictionary, and/or plural category table in the recognition worddictionary memory unit 401, it is possible to generate pluralrecognition dictionaries specialized in specific fields. Regarding wordshighly related to a specific keyword, the frequency of occurrence or theN-gram or class-N-gram probability may be set high in order to increasethe recognition rate of the specific keyword.

Incidentally, the steps in this specification need not be processed intime series in the order described herein and may be processed inparallel or individually.

Meanwhile, with the development of the Internet-related technology, ithas become possible to perform a chat by means of voice (the chathereinafter referred to as voice chat) between personal computers (PC).

If it is possible to display information related to the content of aconversation on a display device of a PC using a voice chat applicationinstalled in the PC, it is possible to improve the convenience of theusers in the chat. In this respect, as an example of the related art,JP-B-3526101 discloses a system that performs speech recognition on thecontent of the conversation of the voice chat, extracts keywords fromthe content of the conversation, searches for related information from adatabase, and displays a search result on a screen.

As another example of the related art, a synchronization system isdisclosed for synchronizing two PCs so that the same screen display canbe displayed by the browsers of the two PCs. However, thesynchronization system is not related to the voice chat technology.

However, in the system disclosed in JP-B-3526101, users have to manuallytransmit information displayed on the screen to the counterpart of thevoice chat in order to share the information displayed on the screen; itis therefore not suitable for communication.

In the synchronization system allowing user to see the same display bythe PC browsers, since the system is not configured in relation to theconversation, every time the topic of the conversation changes, theusers may have to manually input information to search for websitesrelated to the conversation. Therefore, it may be practically difficultto synchronize automatically and efficiently the content of theconversation and all the terminals of the speakers.

The present invention is contrived in view of the above-mentionedsituations. There is a need for providing new and improved voice chatsystem, information processing apparatus, and program that cansynchronize automatically and efficiently keywords related to thecontent of the conversation during a voice chat.

There is also a need for providing new and improved informationprocessing apparatus and program that can synchronize automatically andefficiently keywords contained in broadcast information transmitted froma broadcasting station.

According to a viewpoint of the present invention, there is provided avoice chat system, including: a plurality of information processingapparatuses that performs a voice chat; a keyword extraction databasereferenced by the information processing apparatuses when extractingkeywords from a dialog of the conversation during the voice chat; and asearch engine used by the information processing apparatuses whensearching for the keywords and articles related to the keywords usingthe extracted keywords, wherein at least one information processingapparatus includes: a parameter extraction unit that extracts aparameter from voice data generated from the dialog, the parametercharacterizing the voice data; a keyword extraction unit that recognizesthe generated voice data and extracts the keywords from the voice databased on the parameter and the keyword extraction database; aninformation search unit that searches for the extracted keywords usingthe search engine and acquires a search result for the keywords and thearticles related to the keywords; a display unit that displays a keywordthat is correlated with address information of the search result for thekeyword and an article that is correlated with address information ofthe articles related to the keywords; and a keyword synchronization unitthat transmits the extracted keywords to an information processingapparatus, which is a counterpart of the chat, and performs keywordsynchronization with the counterpart information processing apparatus.

According to the embodiment described above, in an informationprocessing apparatus performing a voice chat, a parameter extractionunit extracts a parameter from voice data generated from a dialog of theconversation during the voice chat, the parameter characterizing thevoice data; a keyword extraction unit recognizes the generated voicedata and extracts keywords from the voice data based on the parameterand a keyword extraction database; an information search unit searchesfor the extracted keywords using a search engine and acquires a searchresult for the keywords and the articles related to the keywords; adisplay unit displays the keywords and the articles related to thekeywords in a correlated manner with address information of the searchresult for the keywords and address information of the articles; and akeyword synchronization unit transmits the extracted keywords to aninformation processing apparatus, which is a counterpart of the chat,and performs keyword synchronization with the counterpart informationprocessing apparatus. In the voice chat system of the embodiments of thepresent invention, speech recognition is automatically performed on thecontent of the conversation during a voice chat to extract keywords andthe keywords are automatically transmitted to a counterpart of the voicechat. Accordingly, it is possible to improve the convenience of users inthe voice chat.

According to another viewpoint of the present invention, there isprovided an information processing apparatus performing voice chat withother information processing apparatus, the apparatus including: aparameter extraction unit that extracts a parameter from voice datagenerated from a dialog of the conversation during the voice chat, theparameter characterizing the voice data; a keyword extraction unit thatrecognizes the generated voice data and extracts keywords from the voicedata based on the parameter and a keyword extraction database; aninformation search unit that searches for the extracted keywords using asearch engine and acquires a search result for the keywords and articlesrelated to the keywords; and a search information accumulation unit thataccumulates the keywords and the articles in a correlated manner withaddress information of the search result for the keywords and addressinformation of the articles, respectively.

According to the embodiment described above, a parameter extraction unitextracts a parameter from voice data generated from a dialog of theconversation during a voice chat, the parameter characterizing the voicedata; a keyword extraction unit recognizes the generated voice data andextracts keywords from the voice data based on a keyword extractiondatabase; an information search unit searches for the extracted keywordsusing a search engine and acquires a search result for the keywords andarticles related to the keywords; and a search information accumulationunit accumulates the keywords and the articles in a correlated mannerwith address information of the search result for the keywords andaddress information of the articles, respectively. The processes fromthe generation of the voice data and the acquisition of the searchinformation are performed automatically. Therefore, users of theinformation processing apparatus are not necessary to perform anyadditional operations, and can automatically acquire information thatcan be used as a topic of the voice chat.

The information processing apparatus may further include a keywordsynchronization unit that transmits the extracted keywords to aninformation processing apparatus, which is a counterpart of the chat,and performs keyword synchronization with the counterpart informationprocessing apparatus. According to the embodiment described above, akeyword synchronization unit transmits the extracted keywords to aninformation processing apparatus, which is a counterpart of a chat, andperforms keyword synchronization. The extracted keywords areautomatically transmitted to the counterpart information processingapparatus of the chat; therefore, counterparts of the voice chat canshare the extracted keywords without needing to perform any additionaloperations.

The information processing apparatus may further include a databasememory unit that stores the keyword extraction database. According tothe embodiment described above, a keyword extraction database is storedin a database memory unit of an information processing apparatus, and itis therefore possible to shorten the time necessary for the informationprocessing apparatus to access the keyword extraction database. As aresult, it is possible to shorten the time necessary for the informationprocessing apparatus to perform the keyword detection.

The search engine may be provided within the information processingapparatus. According to the embodiment described above, a search engineis provided in an information processing apparatus. As a result, it ispossible to shorten the time necessary for the information processingapparatus to access the search engine. As a result, it is possible toshorten the time necessary for the search of information related to thekeywords.

The information processing apparatus may further include a display unitthat displays a keyword that is correlated with address information ofthe search result for the keyword and an article that is correlated withaddress information of the articles related to the keywords. Accordingto the embodiment described above, a keyword and an article related tothe keyword are displayed on a display unit in a correlated manner withaddress information of a search result for the keywords and addressinformation of the article, respectively. Since both the keyword and thearticle related to the keyword are displayed, when the displayed articlecontains information that users are interested, the users can easilyaccess the information.

The information processing apparatus may further include a referencehistory memory unit that stores a reference history of the keywords.According to the embodiment described above, a reference history ofkeywords is stored in a reference history memory unit of an informationprocessing apparatus. The information processing apparatus referencesthe reference history memory unit when extracting keywords from voicedata, thereby enabling keyword detection of high efficiency.

The reference history memory unit may store the referenced keywords in acorrelated manner with an identifier assigned to the respective chat anda counterpart of the chat. According to the embodiment described above,information related to referenced keywords is stored in a referencehistory memory unit in a correlated manner with an identifier assignedto the respective chat and a counterpart of the chat. Therefore, byusing the content of the reference history memory unit, it is possibleto enable keyword detection of higher efficiency.

The keyword extraction unit may extract a keyword placed at a higherrank of the reference history on a preferential basis. Alternatively,the keyword extraction unit may extract a higher-rank search keyword ofthe search engine on a preferential basis. According to the embodimentdescribed above, a keyword placed at a higher rank of reference historyor a higher-rank search keyword of a search engine is extracted on apreferential basis by a keyword detection unit. Since such a keyword ishighly usable as a topic of a voice chat, it is possible to improveaccuracy in speech recognition.

According to a further embodiment of the present invention, there isprovided an information processing apparatus performing voice chat withother information processing apparatus, the at least one informationprocessing apparatus including: a parameter extraction unit thatextracts a parameter from voice data generated from a dialog of theconversation during the voice chat, the parameter characterizing thevoice data; a keyword extraction unit that recognizes the generatedvoice data and extracts keywords from the voice data based on theparameter and a keyword extraction database; an information search unitthat searches for the extracted keywords using a search engine andacquires a search result for the keywords and articles related to thekeywords; and a search information accumulation unit that accumulatesthe keywords and the articles in a correlated manner with addressinformation of the search result for the keywords and addressinformation of the articles, respectively, wherein the informationprocessing apparatus includes a keyword synchronization unit thatreceives the keywords transmitted from the at least one informationprocessing apparatus and performs keyword synchronization with thecorresponding information processing apparatus.

According to the embodiment described above, a keyword synchronizationunit receives keywords from the at least one information processingapparatus, which is a counterpart of a voice chat, having a parameterextraction unit, a keyword extraction unit, an information search unit,and a search information accumulation unit, and performs keywordsynchronization with the information processing apparatus. Since thespeech recognition or the keyword detection, which imposes hugeprocessing load, is executed by at least one information processingapparatus, which is a counterpart of the voice chat, it is possible toperform the voice chat without imposing additional load to the user'sown information processing apparatus.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a parameterextraction function that extracts a parameter from voice data generatedfrom a dialog of the conversation during the voice chat, the parametercharacterizing the voice data; a keyword extraction function thatrecognizes the generated voice data and extracts keywords from the voicedata based on the parameter and a keyword extraction database; aninformation search function that searches for the extracted keywordsusing a search engine and acquires a search result for the keywords andarticles related to the keywords; and a search information storagefunction that stores the keywords and the articles in a correlatedmanner with address information of the search result for the keywordsand address information of the articles, respectively.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a keywordsynchronization function that receives keywords transmitted from atleast one information processing apparatus and performs keywordsynchronization with the corresponding information processing apparatus.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to a still another viewpoint of the present invention, thereis provided an information processing apparatus, including: a broadcasttext information receiving unit that receives broadcast text informationtransmitted from a broadcasting station; a keyword extraction unit thatextracts keywords from the broadcast text information based on a keywordextraction database; an information search unit that searches for theextracted keywords using a search engine and acquires a search resultfor the keywords and the articles related to the keywords; and anexternal display device connection control unit that performs connectioncontrol with an external display device and outputs the keywords, asearch result for the keywords, and articles related to the keywords tothe external display device.

According to the embodiment described above, a broadcast textinformation receiving unit receives broadcast text informationtransmitted from a broadcasting station; a keyword extraction unitextracts keywords from the broadcast text information based on a keywordextraction database; an information search unit searches for theextracted keywords using a search engine and acquires a search resultfor the keywords and the articles related to the keywords; and anexternal display device connection control unit performs connectioncontrol with an external display device and outputs the keywords, asearch result for the keywords, and articles related to the keywords tothe external display device. The processes from the reception of thebroadcast text information and the acquisition of the search informationare performed automatically. Therefore, users of the informationprocessing apparatus are not necessary to perform any additionaloperations, and the acquired search information can be automaticallydisplayed to the external display device.

The broadcast text information receiving unit may acquire receptionchannel information concerning a broadcast channel through which theexternal display device is receiving and the broadcast text informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus. Alternatively, thebroadcast text information receiving unit may acquire reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving, from the external display device connectedto the information processing apparatus, and acquires the broadcast textinformation corresponding to the broadcast channel from the broadcastingstation.

The information processing apparatus may further include a referencehistory memory unit that stores a reference history of the keywords inthe external display device, and the external display device connectioncontrol unit may notify the search engine of a keyword selected by theexternal display device.

The information processing apparatus may further include a keywordsynchronization unit that transmits the extracted keywords to at leastone information processing apparatus and performs keywordsynchronization with the at least one information processing apparatus.

According to a still another viewpoint of the present invention, thereis provided an information processing apparatus, including: a broadcastaudio information receiving unit that receives broadcast audioinformation transmitted from a broadcasting station; a parameterextraction unit that extracts a parameter from voice data contained inthe broadcast audio information, the parameter characterizing the voicedata; a keyword extraction unit that recognizes the voice data andextracts keywords from the voice data based on the parameter and akeyword extraction database; an information search unit that searchesfor the extracted keywords using a search engine and acquires a searchresult for the keywords and articles related to the keywords; and anexternal display device connection control unit that performs connectioncontrol with an external display device and outputs the keywords, thesearch result for the keywords, and the articles related to the keywordsto the external display device.

According to the embodiment described above, a broadcast audioinformation receiving unit receives broadcast audio informationtransmitted from a broadcasting station; a parameter extraction unitextracts a parameter from voice data contained in the broadcast audioinformation, the parameter characterizing the voice data; a keywordextraction unit recognizes the voice data and extracts keywords from thevoice data based on the parameter and a keyword extraction database; aninformation search unit searches for the extracted keywords using asearch engine and acquires a search result for the keywords and articlesrelated to the keywords; and an external display device connectioncontrol unit performs connection control with an external display deviceand outputs the keywords, the search result for the keywords, and thearticles related to the keywords to the external display device. Theprocesses from the reception of the voice data contained in thebroadcast audio information and the acquisition of the searchinformation are performed automatically. Therefore, users of theinformation processing apparatus are not necessary to perform anyadditional operations, and the acquired search information can beautomatically displayed to the external display device.

The broadcast audio information receiving unit may acquire receptionchannel information concerning a broadcast channel through which theexternal display device is receiving and the broadcast audio informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus. Alternatively, thebroadcast audio information receiving unit may acquire reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving, from the external display device connectedto the information processing apparatus, and acquires the broadcastaudio information corresponding to the broadcast channel from thebroadcasting station.

The information processing apparatus may further include a referencehistory memory unit that stores a reference history of the keywords inthe external display device, and the external display device connectioncontrol unit may notify the search engine of a keyword selected by theexternal display device.

The information processing apparatus may further include a keywordsynchronization unit that transmits the extracted keywords to at leastone information processing apparatus and performs keywordsynchronization with the at least one information processing apparatus.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a broadcasttext information receiving function that receives broadcast textinformation broadcast from a broadcasting station; a keyword extractionfunction that extracts keywords from the broadcast text informationbased on a keyword extraction database; an information search functionthat searches for the extracted keywords using a search engine andacquires a search result for the keywords and articles related to thekeywords; and an external display device connection control functionthat performs connection control with an external display device andoutputs the keywords, the search result for the keywords, and thearticles related to the keywords to the external display device.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

According to a still another viewpoint of the present invention, thereis provided a program for allowing a computer to realize: a broadcastaudio information receiving function that receives broadcast audioinformation transmitted from a broadcasting station; a parameterextraction function that extracts a parameter from voice data containedin the broadcast audio information, the parameter characterizing thevoice data; a keyword extraction function that recognizes the voice dataand extracts keywords from the voice data based on the parameter and akeyword extraction database; an information search function thatsearches for the extracted keywords using a search engine and acquires asearch result for the keywords and articles related to the keywords; andan external display device connection control function that performsconnection control with an external display device and outputs thekeywords, the search result for the keywords, and the articles relatedto the keywords to the external display device.

According to the embodiment described above, the computer program isstored in a memory unit of the computer and executed when a CPU of thecomputer reads the program, thereby causing the computer to function asthe information processing apparatus. A computer-readable recordingmedium may be provided having recorded therein the computer program. Therecording medium may be a magnetic disk, an optical disk, amagneto-optical disk, and a flash memory, for example. The computerprogram may be distributed, for example, via a network without using therecording medium.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the attached drawings. Note that,in this specification and the attached drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Third Embodiment

Hereinafter, a voice chat system according to a third embodiment of thepresent invention will be described in detail.

FIG. 29 is an explanatory diagram showing a voice chat system accordingto a third embodiment. The voice chat system 1010 includes acommunication network 1012, a keyword extraction database 1030, a searchengine 1040, and information processing apparatuses 1020A and 1020B(hereinafter, sometimes, collectively referred to as informationprocessing apparatus or apparatuses 1020).

The communication network 1012 is a communication network that connectsthe information processing apparatus 20, the keyword extraction database1030, and the search engine 1040 to enable bidirectional orunidirectional communication therebetween. The communication network1012 may be constructed, for example, by a public network, such asInternet, telephone network, satellite communication network, orbroadcast communication channel, or a private network, such as WAN (WideArea Network), LAN (Local Area Network), IP-VPN (InternetProtocol-Virtual Private Network), Ethernet (registered trademark), orwireless LAN. The communication network 1012 may be wired or wireless.

The information processing apparatus 1020 performs a chat (a voice chat)by means of voice with another information processing apparatus 1020connected thereto via the communication network 1012. The informationprocessing apparatus 1020 can request the keyword extraction database1030 and the search engine 1040 connected thereto via the communicationnetwork 1012 to perform referencing of a database or search ofinformation via the communication network 1012.

The another information processing apparatus 1020 performing the voicechat may be connected thereto via the communication network 1012, asshown in the drawing. Alternatively, the another information processingapparatus 1020 may be directly connected, not via the communicationnetwork 1012, to a USB (Universal Serial Bus) port, an IEEE 1394 portsuch as i.Link, an SCSI (Small Computer System Interface) port, anRS-232C port, and the like.

In the shown example shown in the drawing, the information processingapparatus 1020 is a desktop PC; however, in the present embodiment, theinformation processing apparatus 1020 may be a notebook PC. In thepresent embodiment, the information processing apparatus 1020 is notlimited to the example described above but may be constructed, forexample, by a television set-top checkbox, an information appliance suchas a home-use game machine, a mobile phone, a PDA (Personal DigitalAssistant), and the like as long as it is a device capable of having afunction of communicating via a network. Additionally or alternatively,the information processing apparatus 20 may be a portable device, suchas a portable game machine, a PHS, or a portable video/audio player,which is carried by a user who leased it.

In FIG. 29, only two information processing apparatuses 1020 areconnected to the communication network 12. However, the presentembodiment is not limited to the example, and a plurality of informationprocessing apparatuses 1020 may be connected to the communicationnetwork 1012.

The keyword extraction database 1030 is a database that the informationprocessing apparatus 1020 references when the information processingapparatus 1020 extracts keywords from voice data obtained from thecontent of the conversation during a voice chat. In the keywordextraction database 1030, a variety of information such as theconcatenation relationship of the pronunciations, phonemes, andsyllables of a word serving as a keyword and the category of the keywordare described. For example, in the keyword extraction database 1030, thehigher-rank search keywords of the search engine or the terms that arefrequently used as a topic in the blogs are described as keywords. Thekeyword extraction database 1030 may be a dynamic database that isupdated on an as needed basis in accordance with the change of thehigher-rank search keywords of the search engine (search server) or theterms frequently used as a topic in the blogs; alternatively, thekeyword extraction database 1030 may be a static database. The keywordsdescribed in the keyword extraction database 1030 may be processed witha probabilistic latent semantic analysis (PLSA) model or the like andtransformed into a form of a suitable topic vector. Here, the topicvector refers to a vector space representation of a topic and is used todetermine the commonness of the topic. In addition, recognition weightinformation described later may be added to the keywords described inthe keyword extraction database 1030.

The concatenation relationship of the pronunciations, phonemes, andsyllables of a word serving as a keyword refers to a relationshiprepresenting how the words described as the keywords in the keywordextraction database 1030 are concatenated (connected) with each other interms of their pronunciations, phonemes, and syllables. As a method ofdescribing the concatenation relationship, statistical wordconcatenation probability (n-gram or class n-gram), generation grammar,finite state automaton (FSA) or the like may be used.

The search engine 1040 is a database of a website that users can searchfor information available through the Internet using keywords or thelike. Here, the information may be open to the public or closed. In thepresent embodiment, the search engine 1040 may provide a full-textsearch service that allows search of the full text of information instore using a keyword; or it may be a directory service that allowssearch of information classified by categories.

(Configuration of Information Processing Apparatus 20)

Next, the configuration of the information processing apparatus 1020according to the present embodiment will be described briefly withreference to FIG. 30.

In the following descriptions, the term “word” refers to a unit that isconveniently treated as a single word in a speech recognition process.It is not necessarily the same as a linguistic word. For example,

(uttered as taroukun)” may be treated as one word, or may be treated astwo words in the form of “tarou” and “kun.” Further, a larger unit

(uttered as konnichiwa taroukun)” may be treated as one word.

Additionally, the term “phoneme” refers to a unit that is convenientlytreated as a single unit in an acoustic point of view. It is notnecessarily the same as a phonetic syllable or phoneme. For example, inthe word

(uttered as tou kyou),” the part “tou” may be represented by threephoneme symbols “t/o/u,” or “to:,” which is a prolonged sound of “o.”Further, the part “tou” may be represented by “t/o/o.” In addition, asymbol representing a silence may be adopted. Furthermore, symbols thatclassify the silence as “a silence before an utterance”, “a shortsilence interposed between utterances”, “a silence in an utterance”, and“a silence corresponding to

(uttered as tsu)” may be adopted.

FIG. 30 is an explanatory diagram showing the hardware configuration ofthe information processing apparatus 20 according to the presentembodiment. The information processing apparatus 1020 includes a centralprocessing unit (CPU) 1201, a read only memory (ROM) 1203, a randomaccess memory (RAM) 1205, a host bus 1207, a bridge 1209, an externalbus 1211, an interface 1213, an input device 1215, an output device1217, a storage device 1219, a drive 1221, and a communication device1233.

The CPU 1201 functions as an arithmetic processing unit and a controlunit. The CPU 1201 controls the overall or a part of the internaloperations in the information processing apparatus 120 in accordancewith various programs recorded in the ROM 1203, the RAM 1205, thestorage device 1219, or a removable recording medium 1014. The ROM 1203stores the programs, arithmetic parameters, and so on used by the CPU1201. The RAM 1205 temporarily stores the programs used in execution ofthe CPU 1201 and the parameters appropriately varying in the executionof the CPU 1201. The CPU 1201, the ROM 1203, and the RAM 1205 areconnected to each other via the host bus 1207, such as a CPU bus.

The host bus 1207 is connected to the external bus 1211, such asPeripheral Component Interconnect (PCI) bus, via the bridge 1209.

The input device 1215 includes an operation unit, such as a mouse, akeyboard, a touch panel, buttons, switches, and a lever, operated by auser and a voice input unit, such as a microphone and a headset. Theinput device 1215 may be a remote control unit (a so-called remotecontroller) that uses an infrared ray or other electronic wave or may bean externally connected device such as a mobile phone or a PDAcorresponding to the operation of the information processing apparatus1020. The input device 1215 may be an input control circuit thatgenerates an input signal based on information input by the user usingthe operation unit or the voice input unit and outputs the generatedinput signal to the CPU 1201. The user of the information processingapparatus 1020 operates the input device 1215 to input a variety of datato the information processing apparatus 1020 or to instruct theinformation processing apparatus 1020 to perform processing operations.

The output device 1217 may be constructed, for example, by a displayunit, such as a cathode ray tube (CRT) display unit, a liquid crystaldisplay (LCD) unit, a plasma display panel (PDP) unit, anelectro-luminescence (EL) display unit, or a lamp, an audio output unitincluding a speaker and a headphone, and a device such as a printer, amobile phone, or a fax machine, which can notify users of acquiredinformation in a visible or audible manner. The output device 1217outputs, for example, a variety of information searched by a searchserver. Specifically, the display unit displays a search result of thevariety of information by the search server as a text or an image.Meanwhile, the audio output unit converts the voice data that is playedback into a voice to output the voice.

The storage device 1219 is a data storage device which is an example ofa storage unit of the information processing apparatus 1020 according tothe present embodiment. The storage device 1219 is constructed, forexample, by a magnetic storage unit such as a hard disk drive (HDD), asemiconductor storage device, an optical storage device, amagneto-optical storage device, and the like. The storage device 1219stores the programs or a variety of data executed by the CPU 1201 and avariety of data acquired from the outside.

The drive 1221 is a reader-writer for a storage medium. The drive 1221is incorporated in the information processing apparatus 1020 or isexternally attached to the information processing apparatus 1020. Thedrive 1221 reads out information recorded in the removable storagemedium 1014, such as a magnetic disk, an optical disk, a magneto-opticaldisk, or a semiconductor memory, which is loaded in the drive 1221, andoutputs the readout information to the RAM 1205. The drive 1221 canrecord information in the removable storage medium 1014, such as amagnetic disk, an optical disk, a magneto-optical disk, or asemiconductor memory, which is loaded in the drive 1221. The removablerecording medium 1014 may be, for example, a DVD medium, a HD-DVDmedium, a Blu-ray medium, a compact flash (CF), a memory stick, or asecure digital (SD) memory card. The removable recording medium 1014 maybe, for example, an electronic device or an integrated circuit (IC) cardhaving mounted thereon a non-contact type IC chip.

The communication device 1223 is a communication interface constructedby a communication device used for connecting to the communicationnetwork 1012. The communication device 1223 may be, for example, acommunication card for wired or wireless local area network (LAN),Bluetooth or wireless USB (WUSB), a router for optical communication, arouter for asymmetric digital subscriber line (ADSL), or a modem forvarious communication protocols. The communication device 1223 transmitsand receives a variety of information to and from the Internet or othercommunication devices while transmitting and receiving informationrelated to a voice chat with another information processing apparatus1020. The communication network 1012 connected to the communicationdevice 1223 may be constructed by a network such as the Internet, a homeLAN, an infrared communication, or a satellite communication, which isconnected in a wired or wireless manner.

With the configuration described above, the information processingapparatus 1020 can perform a voice chat with another informationprocessing apparatus directly connected to the information processingapparatus 1020 or with another information processing apparatusconnected thereto via the communication network 1012 while acquiring avariety of information from the keyword extraction database 1030 thesearch engine 1040 or the like connected thereto via the communicationnetwork 1012. Moreover, the information processing apparatus 1020 cantake out information stored in the information processing apparatus 1020using the removable recording medium 1014.

Hereinabove, an example of the hardware configuration that can realizethe functions of the information processing apparatus 1020 according tothe present embodiment has been described. The components describedabove may be constructed using a general-purpose element or may beconstructed by a specialized hardware that is specialized to thefunctions of the respective components. Therefore, the hardwareconfiguration can be appropriately modified in accordance with the levelof technology at the time of practicing the present embodiment. Thehardware configuration described above is merely for illustrationpurposes, and the invention is by no means limited to this. Somecomponents such as the host bus 1207, the external bus 1211, or theinterface 1213 may be omitted depending on the form of use.

Next, the configuration of the information processing apparatus 1020according to the present embodiment will be described in detail. In thefollowing descriptions, two information processing apparatuses 1020performing a voice chat will be referred to as a first informationprocessing apparatus 1020A and a second information processing apparatus1020B. The first and second information processing apparatuses 1020A and1020B generate voice data from the sound of the respective users of theinformation processing apparatuses and transmit the voice data to theother information processing apparatus, which is a counterpart of thevoice chat. FIG. 31 is a block diagram for explaining the configurationof the third information processing apparatus 1020A according to thefirst embodiment.

The first information processing apparatus 1020A according to thepresent embodiment includes a voice input unit 1231, a speechrecognition unit 1233, a voice conversation control unit 1239, a voiceoutput unit 1241, an information search unit 1243, a keywordsynchronization unit 1245, a display unit 1247, a communication unit1249, and a memory unit 1251.

The voice input unit 1231 is an interface that inputs, to the firstinformation processing apparatus 20A, a dialog of the conversationduring a voice chat which is the speech uttered by the user of the firstinformation processing apparatus 1020A. The voice input unit 1231 isconstructed, for example, by an input device such as a microphone or aheadset, connected to the first information processing apparatus 1020A.The speech of the users uttered to the microphone or headset isautomatically input in real time to the first information processingapparatus 1020A. The input analog signal is sampled and quantizedthrough AD conversion and transmitted as voice data, which is a digitalsignal, to the speech recognition unit 1233 via the voice input unit1231.

The speech recognition unit 1233 is constructed, for example, by CPU,ROM or RAM. The speech recognition unit 1233 performs real-time basedspeech recognition based on the voice data transmitted from the voiceinput unit 1231. The speech recognition unit 1233 further includes aparameter extraction unit 1235 and a keyword extraction unit 1237.

The parameter extraction unit 1235 extracts feature parameters such asMel Frequency Cepstrum Coefficients (MFCC) and time difference parameterthereof, spectrum of the voice data, power linear predictivecoefficients, cepstrum coefficients, and a line spectrum pair, from eachframe (at appropriate time intervals) of the generated voice data.

The parameter extraction unit 1235 transmits the extracted featureparameters to the keyword extraction unit 1237. The parameter extractionunit 1237 may store, in the memory unit 1251 described later, theextracted feature parameters.

The keyword extraction unit 1237 extracts keywords from the voice data,which is a digital signal of the speech uttered by the user of the firstinformation processing apparatus 1020A, based on the keyword extractiondatabase 1030 and the feature parameters generated and extracted by theparameter extraction unit 1235. When the keyword extraction unit 1237extracts the keywords, the keyword extraction unit 1237 can referencethe keyword extraction database 1030 connected to the communicationnetwork 1012 via the communication unit 1249.

A plurality of keywords is contained in the sentences of the speechuttered by the users during the voice chat. The keyword extraction unit1237 automatically extracts all the keywords existing in the sentencesof the speech. The keyword extraction unit 1237 transmits the extractedkeywords to the information search unit 1243 described later. Thekeyword extraction unit 1237 may store the extracted keywords in thememory unit 1251.

The method of the speech recognition unit 1233 recognizing the voicetransmitted from the voice input unit 1231 and extracting keywords fromthe recognized voice will be described later.

The voice conversation control unit 1239 is constructed, for example, byCPU, ROM, and RAM, and controls the voice chat with the secondinformation processing apparatus 1020B connected via the communicationnetwork 1012. The voice conversation control unit 1239 receives thevoice data generated by the speech input unit 1231 and transmits thevoice data to the second information processing apparatus 1020B via thecommunication unit 1249. The voice conversation control unit 1239receives voice data transmitted from the second information processingapparatus 1020B via the communication unit 1249 and transmits the voicedata to the voice output unit 1241. The voice conversation control unit1239 may be configured to store, every time the voice chat is performed,the date the voice chat was performed, an identifier for identifying thevoice chat, and an identifier for identifying a counterpart of the voicechat in the memory unit 1251 in a correlated manner.

The voice conversation control unit 1239 may be constructed by aspecialized hardware that is specialized to the voice conversationcontrol and may be provided as an application program such as a voicechat program.

The voice output unit 1241 is an interface that receives the voice dataof the speech uttered by the user of the second information processingapparatus 1020B and inputs the received voice data to the firstinformation processing apparatus 1020A. The voice output unit 1241 isconstructed, for example, by a speaker or an earphone which is an outputdevice connected to the first information processing apparatus 1020A.

The voice data received via the communication unit 1249 from the secondinformation processing apparatus 1020B is output to the user of thefirst information processing apparatus 1020A via the voice output unit1241.

The information search unit 1243 stores, in the memory unit 1251, thekeywords transmitted from the keyword extraction unit 1237 and the timeat which the keywords were transmitted from the keyword extraction unit1237 in a correlated manner. The information search unit 1243 determineswhether or not a keyword synchronization process is to be performed onthe keywords transmitted from the keyword extraction unit 1237. When itis determined that the keyword synchronization process should beperformed, the information search unit 1243 transmits the keywords tothe keyword synchronization unit 1245, thereby requesting the executionof the keyword synchronization process. The information search unit 1243accesses the search engine 1040 via the communication unit 1249 andperforms information search of the keywords transmitted from the keywordextraction unit 1237, thereby acquiring a search result for the keywordsand the articles related to the keywords. The information search unit1243 stores the obtained search result in the search result storage unit1253 of the memory unit 1251 and transmits the search result to thedisplay unit 1247. Here, the search result that the information searchunit 1243 acquires from the search engine 1040 includes a title or anURL of information about the search keyword in the search engine 1040and a metadata of information, such as a genre of the information.

When requested by the display unit 1247 to acquire more detailedinformation about a specific keyword or an article related to thekeyword, the information search unit 1243 accesses the search engine1040 via the communication unit 1249 to acquire the more detailedinformation and stores the specific keyword notified from the displayunit 1247 in the reference history memory unit 1255 of the memory unit1251.

The keyword synchronization unit 1245 transmits the keywords extractedby the keyword extraction unit 1237 from the voice data to the secondinformation processing apparatus 1020B via the communication unit 1249,thereby synchronizing the first and second information processingapparatuses 1020A and 1020B. The keyword synchronization process can beperformed not only in the direction from the first informationprocessing apparatus 1020A to the second information processingapparatus 1020B, but also from the second information processingapparatus 1020B to the first information processing apparatus 1020A inthe following manner. That is, the first information processingapparatus 1020A may response to the keyword synchronization processinitiated by the second information processing apparatus 1020B so thatthe keywords transmitted from the second information processingapparatus 1020B are received to the first information processingapparatus 1020A.

The display unit 1247 displays the information search result transmittedfrom the information search unit 1243 to an output device such as adisplay or the like provided to the first information processingapparatus 1020A via a browser application, for example. The informationthat the information search unit 1243 acquires from the search engine1040 contains a URL or the like of the information or articles in thesearch engine 1040. Therefore, when the user of the first informationprocessing apparatus 1020A selects the displayed information by means ofan input device such as a mouse or a keyboard connected to the firstinformation processing apparatus 1020A, the display unit 1247 requeststhe information search unit 1243 to acquire the details of the selectedinformation.

The communication unit 1249 is a communication device installed in thefirst information processing apparatus 1020A, for example. Thecommunication unit 1249 relays communication of information via thecommunication network 1012 between the first information processingapparatus 1020A, specifically, the keyword extraction unit 1237, thevoice conversation control unit 1239, the information search unit 1243,and the keyword synchronization unit 1245, and the external device ofthe first information processing apparatus 1020A, specifically thekeyword extraction database 1030, the search engine 1040 or the secondinformation processing apparatus 1020B. Moreover, the communication unit1249 can communicate information with other information processingapparatus that are directly connected to the first informationprocessing apparatus 1020A not via the communication network 1012.

The memory unit 1251 is a storage device installed in the firstinformation processing apparatus 1020A, for example, and stores thereindata such as the keywords extracted by the keyword extraction unit 1237or the search information acquired by the information search unit 1243.Besides these data, the memory unit 1251 can store therein the voicedata generated by the voice input unit 1231 or a variety of databases.Furthermore, the memory unit 1251 may further store therein a variety ofparameters that need be stored when the first information processingapparatus 1020A performs a process and progress information of theprocess. The memory unit 1251 is accessible when the speech recognitionunit 1233, the voice conversation control unit 1239, the informationsearch unit 1243, the keyword synchronization unit 1245, or the likefreely performs reading or writing to the memory unit 1251. The memoryunit 1251 further includes a search information accumulation unit 1253and a reference history memory unit 1255.

The search information accumulation unit 1253 accumulates the searchinformation acquired by the information search unit 1243 and theinformation acquisition data in a correlated manner. When it is desiredto display once-acquired search information, the information stored inthe search information accumulation unit 1253 can be referenced todisplay the once-acquired search information.

The reference history memory unit 1255 stores, as a reference history,the keywords that the user of the first information processing apparatus1020A has referenced among the keywords or articles displayed on thedisplay unit 1247 for more detailed information. The reference historyis data that includes the referenced keywords, weight information of thereferenced keywords, an identifier of the voice chat itself havingreferenced the keywords, and a counterpart of the voice chat. Thereference history stored in the reference history memory unit 1255 maybe used when the keyword extraction unit 1237 extracts the keywords.

The information search unit 1243, the keyword synchronization unit 1245,and the display unit 2147 may be constructed by a specialized hardwarethat is specialized to the respective function and may be provided as anapplication program such as a speech recognition program.

The configuration of the second information processing apparatus 1020Bis substantially the same as the first information processing apparatus1020A, and descriptions thereof will be omitted.

Hereinabove, an example of the function of the information processingapparatus 1020 according to the present invention has been described.The components described above may be constructed using ageneral-purpose element or circuit or may be constructed by aspecialized hardware that is specialized to the functions of therespective components. The whole functions of the components may beexecuted by a CPU or the like. Therefore, the hardware configuration canbe appropriately modified in accordance with the level of technology atthe time of practicing the present embodiment.

(Speech Recognition Method and Keyword Extraction Method)

Hereinafter, a method of the speech recognition unit 1233 performingspeech recognition to extract keywords from a speech recognition resultwill be briefly described with reference to FIG. 32. The speechrecognition method and keyword extraction method used by the speechrecognition unit 1233 according to the present embodiment is not limitedto the example described below. FIG. 32 is a flowchart for explaining anexample of the speech recognition method and keyword extraction methodused by the speech recognition unit 1233 according to the presentembodiment.

The speech recognition unit 1231 generates voice data from the speech ofthe user of the first information processing apparatus 1020A inputthereto. In the voice input unit 1231, the input user's speech isAD-converted to sample and quantize the speech, which is an analogsignal, and the analog speech signal is converted into voice data, whichis a digital signal (Step S1101). Upon completion of the conversion tothe voice data, the voice input unit 1231 transmits the generated voicedata to the speech recognition unit 1233 and the voice conversationcontrol unit 1239.

Subsequently, the parameter extraction unit 1235 extracts featureparameters such as Mel Frequency Cepstrum Coefficients (MFCC) and timedifference parameter thereof, spectrum of the voice data, power linearpredictive coefficients, cepstrum coefficients, and a line spectrumpair, from each frame (at appropriate time intervals) of the generatedvoice data (Step S1103).

The keyword extraction unit 1237 calculates a word sequence that isclosest to the speech (input voice) input to the voice input unit 1231as a recognition result and extracts keywords from the recognitionresult based on the feature parameters acquired from the parameterextraction unit 1235, for example, by referencing the keyword extractiondatabase 1030, an acoustic model, a language model, and dictionariesused in the acoustic model or the language model.

Here, the acoustic model stores therein a model that represents anacoustic feature of individual phonemes, syllables, or the like of thespeech to be recognized. As the acoustic model, a Hidden Markov Model(HMM), for example, can be used. As the acoustic model, two models, onefor quiet environment (an acoustic model capable of providing highrecognition rate under quiet environment) and the other for noisyenvironment (an acoustic model capable of providing favorablerecognition rate under noisy environment) may be provided so that eitherone of the models can be referenced depending on the environment.

The language model stores therein a model that describes information(concatenation information) representing how the words registered ineach dictionary are concatenated (connected). As the language model,statistical word concatenation probability (n-gram or class n-gram),generation grammar, finite state automaton (FSA) or the like may beused.

The language model may store therein concatenation information of acategory of the words as well as the concatenation information of thewords. For example, when “a category to which the words representingpersonal names belong” is represented as a symbol “_personal name” and“a category to which the words representing food belongs” is representedas a symbol “_food_,” the language model also describes theconcatenation information of “_personal name” and “_food_”; that is,concatenation between categories and concatenation between the categoryand the words stored in advance in the dictionary are also described.

Therefore, concatenation information of the words that are not containedin the language model can be acquired. For example, when acquiringconcatenation information between

(uttered as ichiro)” and

(a particle, uttered as wa),” even though the concatenation informationof

(uttered as ichiro) “is not described in the language model, if it ispossible to know that the

(uttered as ichiro)” belongs to a category represented as a symbol“_personal name_,” it is possible to acquire the concatenationinformation between

(uttered as ichiro) “and

(a particle, uttered as wa)” by acquiring the concatenation informationbetween “_personal name_” and

(a particle, uttered as wa).

Upon receiving the voice data from the voice input unit 1231, thekeyword extraction unit 1237 generates a word sequence by connectingsome of the words in terms of the pronunciations or phonemes of thewords based on the acoustic model. The keyword extraction unit 1237calculates an acoustic score of the generated word sequence based on theacoustic model (Step S1105). Here, the acoustic store is a numeric valuethat represents how closely the word sequence, which is a result of thespeech recognition, resembles the input voice in terms of sound (fromthe acoustic point of view). The keyword extraction unit 1237 selects apredetermined number of word sequence having higher acoustic score basedon the calculated acoustic score.

The keyword extraction unit 1237 may perform matching using a Viterbidecoder based on beam search or a stack decoder base on A* search.Additionally or alternatively, a so-called keyword spotting method maybe used in the matching. If “recognition weight” information is addedthe variety of word dictionaries referenced by the keyword extractionunit 1237, a weight may be applied to a language score described laterand the recognition result may be ranked by the weighted score. Therecognition weight information is information that describes arecognition weight, which is a correction factor (weight factor) used incalculation of the language score; as the recognition weight has agreater value, the correction value of the language score increases, andthus keywords having a greater recognition weight are highly likely tobe adopted as the recognition result. For example, a keyword having arecognition weight of 10 will be speech-recognized with a probabilityten times higher than a keyword (i.e., an unweighted keyword) having arecognition weight of 1.

Regarding the determining of the recognition weight, rank information inthe search keyword list acquired from the search engine 1040 orfrequency of occurrence of keywords in the output of the speechrecognition result may be used. Since the search keyword list is a listof search keywords placed on the higher rank in the search engine 1040,ranks may be assigned to the keywords in the descending order of theirfrequencies of occurrence in the search; a predetermined recognitionweight is determined in order of the rank.

Specifically, predetermined coefficients are assigned to the keywords inthe descending order of their frequencies of occurrence in the search,and a normalized keyword frequency is multiplied with the assignedcoefficients, thereby obtaining the recognition weight. Regarding theacquisition of the search keyword list and the sub-keyword, and theadding of the keyword information, a thesaurus, an ontology database, anencyclopedia, a Japanese language dictionary, or a morphologicalanalysis tool, which is stored in a server connected thereto via thecommunication network 1020, may be used instead of the search engine1040. The search engine 1040 may be used in addition to the thesaurus,the ontology database, the encyclopedia, the Japanese languagedictionary, and the morphological analysis tool.

Regarding the determining of the recognition weight, information onwhether or not the user of the first information processing apparatus1020A has performed the search of the keywords obtained as the speechrecognition result using the search engine 1040 or not, or thepreference of the user of the first information processing apparatus1020A may be used.

Subsequently, the keyword extraction unit 1237 calculates a languagescore of each selected word sequence based on the language model (StepS1109). Here, the language score is a numeric value for determiningwhether or not the selected word sequence is suitable for the languagemodel. If grammar or finite state automaton is used as the languagemodel, the language score is a numeric value that indicates whether ornot the word sequence is acceptable to the language model. If astatistical language model is used as the language model, the languagescore is a generation probability of the word sequence. Specifically, ifgrammar or finite state automaton is used as the language model, whenthe word sequence is acceptable to the language model, the languagescore of the word sequence is “1”; when the word sequence is notacceptable to the language model, the language score of the wordsequence is “0.” When the statistical language model such as n-gram orclass n-gram is used as the language model, the generation probabilityof the word sequence is used as the language score. The detailed methodof calculating the language score is described in Japanese PatentApplication No. 2001-382579 filed by the present applicant(corresponding to JP-A NO. 2003-186494).

Subsequently, the keyword extraction unit 1237 integrates the acousticscore and the language score calculated in the previous steps and sortsand selects the word sequences by the score (Step S1111), therebydetermining the word sequence having the greatest integrate score as arecognition result (Step S1113). Specifically, the keyword extractionunit 1237 determines as the recognition result, the word sequence thatmaximizes the product or the logarithmic sum of the acoustic scoreacquired from the acoustic model and the language score acquired fromthe language model. When information such as a recognition weight ofwords is added to the dictionaries used in the language model, alanguage score having the recognition weight information incorporatedtherein may be used.

With this, a word sequence that is most feasible from the acoustic andlinguistic points of view is determined as the recognition result.

Subsequently, the keyword extraction unit 1237 accesses the keywordextraction database 1030 via the communication unit 1249 to compare thespeech recognition result with the keywords registered in the keywordextraction database 1030 (Step S1115). If a word registered in thekeyword extraction database 1030 is contained in the speech recognitionresult, the keyword extraction unit 1237 determines that the wordcontained in the speech recognition result is to be extracted (StepS1117).

The keyword extraction unit 1237 may be configured to access the secondinformation processing apparatus 1020B, which is a counterpart of thevoice chat, before accessing the keyword extraction database 1030, so asto exchange the recognition result of the voice chat. For example, byexchanging voice information or the speaker's way of talking, it ispossible to increase the accuracy of the speech recognition. In order tovalidate the speech recognition results of the information processingapparatuses, the topic vectors of the speech recognition results may beexchanged.

By using the speech recognition method and the keyword extraction methoddescribed above, it is possible not only to appropriately recognize thecontent of the conversation during the voice chat but also appropriatelyextract keywords from the speech recognition result.

(Keyword Synchronization Method)

Next, a keyword synchronization method in the voice chat systemaccording to the present embodiment will be described in detail withreference to FIG. 33. FIG. 33 is a flowchart for explaining the keywordsynchronization in the voice chat system according to the thirdembodiment. FIG. 33 shows the case in which the user of the firstinformation processing apparatus 1020A utters sounds to the secondinformation processing apparatus 1020B.

When the user of the first information processing apparatus 1020A utterssounds toward the voice input unit 1231 such as a microphone or aheadset connected to the first information processing apparatus 1020A,the voice input unit 2131 generates voice data from the sound uttered bythe user (Step S1201). The generated voice data is transmitted to theparameter extraction unit 1235 and the voice conversation control unit1239. The voice conversation control unit 1239 transmits the generatedvoice data to the second information processing apparatus 1020B via thecommunication unit 1249 so that a voice conversation is made between thefirst and second information processing apparatuses 1020A and 1020B(Step S1203).

The parameter extraction unit 1235 transmits the voice data and avariety of extracted parameters to the keyword extraction unit 1237, andthe keyword extraction unit 1237 performs speech recognition on thevoice data in order to extract keywords from a speech recognitionresult. Subsequently, the keyword extraction unit 1237 exchanges thespeech recognition result with the second information processingapparatus 1020B via the communication unit 1249 (Step S1205) in order toincrease the accuracy of the speech recognition result. Thereafter, thekeyword extraction unit 1237 accesses the keyword extraction database1030 connected to the communication network 1012 via the communicationunit 1249 (Step S1207). The keyword extraction database 1030 issues areference permit to the first information processing apparatus 1020A,allowing referencing databases registered therein (Step S1209). Thekeyword extraction unit 1237 of the first information processingapparatus 1020A extracts keywords by referencing the keyword extractiondatabase 1030 (Step S1211).

When extracting the keywords, the keyword extraction unit 1237 may beconfigured to access the search engine 1040 or the like and extract thehigher-rank search keywords of the search engine 1040 or the terms thatare frequently used as a topic in the blogs on a preferential basis. Thetopics of the voice chat are often topics that are in fashion at thetime of the voice chat. Therefore, keywords related to such topics arehighly likely to be the higher-rank search keywords of the search engine1040 or the terms that are frequently used as a topic in the blogs.Therefore, by extracting such keywords on a preferential basis, thekeyword extraction can be performed more efficiently.

Subsequently, the keyword extraction unit 1237 transmits the extractedkeywords to the information search unit 1243 and the information searchunit 1243 stores the transmitted keywords in the memory unit 1251 in acorrelated manner with the transmission time (Step S1213). Subsequently,the information search unit 1243 determines whether or not thetransmitted keywords are an old keywords that were extracted beforeduring the current voice chat (Step S1215). If the transmitted keywordsare new keywords that were not extracted before, the keyword extractionunit 1237 newly registers the keywords (Step S1219).

If the transmitted keywords are old keywords, the information searchunit 1243 searches for the transmission time of the old keywords anddetermines whether or not a predetermined period (for example, 5minutes) has expired after the transmission time (Steps S1217). Thepredetermined period used in the above determining step is not limitedto this and may be set to an arbitrary period. If the predeterminedperiod has not expired after the transmission time of the old keywords,the information search unit 1243 rejects the transmitted keywords, andthe keyword extraction process is finished. If the predetermined periodhas expired after the transmission time of the old keywords, theinformation search unit 1243 updates the transmission time of the newkeywords and newly registers the keywords (Step S1219).

When the keywords are newly registered, the information search unit 1243transmits the newly registered keywords to the keyword synchronizationunit 1245. Upon receiving the keywords, the keyword synchronization unit1245 transmits the transmitted keywords to the second informationprocessing apparatus 1020B via the communication unit 1249 (Step S1221).With such transmitting process, a synchronization process thatsynchronizes the keywords extracted by the first information processingapparatus 1020A to the second information processing apparatus 1020B,which is a counterpart of the voice chat, is made. Here, thesynchronization process only involves exchanging of the keywords.Therefore, there is no need to prepare a synchronization area on thememory of the information processing apparatus.

In the first information processing apparatus 1020A in which the newkeywords are registered, the information search unit 1243 accesses thesearch engine 1040 connected to the communication network 1012 via thecommunication unit 1249 (Step S1223) and acquires the search result forthe new keywords and metadata that describes URLs or the like of thearticles related to the keywords (Step S1225). Thereafter, theinformation search unit 1243 stores the acquired information in thesearch information accumulation unit 1253 and transmits the acquiredinformation to the display unit 1247. Subsequently, the display unit1246 displays the transmitted information on a display device via abrowser or the like (Step S1227).

In the second information processing apparatus 1020B to which thekeywords are transmitted, determinations on whether or not the keywordsare old and, if old, whether or not a predetermined period has expiredare performed independent from the first information processingapparatus 1020A. If the keywords are not old, or although old if thepredetermined period has expired, the second information processingapparatus 1020B newly registers the transmitted keywords.

Thereafter, the second information processing apparatus 1020B accessesthe search engine 1040 (Step S1229) and acquires metadata that describesURLs or the like of the transmitted keywords (Step S1231). As same inthe first information processing apparatus 1020A, the second informationprocessing apparatus 1020B stores the acquired information in the searchinformation accumulation unit 1253 and transmits the acquiredinformation to the display unit 1247. Subsequently, the display unit1247 displays the transmitted information on a display device via abrowser or the like (Step S1233).

The process steps from the step of inputting the content of theconversation during the voice chat into the first information processingapparatus 1020A to the step of synchronizing keywords to display thesearch result for information related to the keywords are automaticallyperformed by the first information processing apparatus 1020A.Therefore, the user of the first information processing apparatus 1020Adoes not need to do any special operations for the speech recognition,keyword detection, and keyword synchronization process. Accordingly, theuser of the first information processing apparatus 1020A can concentrateon the voice chat. Meanwhile, in the second information processingapparatus 1020B, the keyword synchronization process and the informationsearch result displaying process are also automatically performed. Theuser of the second information processing apparatus 1020B does not needto do any special operations for such process and can concentrate on thevoice chat.

As described above, the first information processing apparatus 1020Aperforms keyword extraction based on the sound uttered by the user ofthe first information processing apparatus 1020A and then performskeyword synchronization with respect to the second informationprocessing apparatus 1020B. As a result, the first informationprocessing apparatus 1020A that has performed keyword extraction and thesecond information processing apparatus 1020B, in which the keywordsynchronization has been made, perform search using the search engine1040 and display the search results in an independent manner from eachother. With such a process, on the display devices of the first andsecond information processing apparatuses 1020A and 1020B, the samekeywords and the same articles related to the keywords are displayedsubstantially simultaneously with small time lag corresponding to theinherent communication delay. Since the information related to thekeywords is also displayed, it is possible to automatically provideinformation that can be used as a topic of the voice chat and to thusbroaden the conversation of the voice chat.

It has been described for the case in which the user of the firstinformation processing apparatus 1020A utters sounds to the secondinformation processing apparatus 1020B. However, the above-describedprocess can be similarly performed for the case in which the user of thesecond information processing apparatus 1020B utters sounds to the firstinformation processing apparatus 1020A. In this case, the secondinformation processing apparatus 1020B performs generation of the voicedata and extraction of the keywords, obtains newly registered keywords,and performs the keyword synchronization process with respect to thefirst information processing apparatus 1020A. As a result, search of thekeyword related information and display of the search result areperformed by the first and second information processing apparatuses1020A and 1020B in an independent and parallel manner similar to themanner described above. In this way, the inputting (generating of thevoice data) of the conversation during a voice chat and the extractingof the keywords are processed by the respective information processingapparatuses in an independent and parallel manner.

When the voice chat between the first and second information processingapparatuses 1020A and 1020B ends, the keywords and the temporaryinformation related to the keywords registered in the informationprocessing apparatuses 1020A and 1020B are deleted, and new keywords areregistered in later use.

In the above description, the keyword extraction database 1030 isindependently connected to the communication network 1012 connected tothe first information processing apparatus 1020A. The keyword extractiondatabase 1030 may be provided in the first information processingapparatus 1020A. In this case, the keyword extraction database 1030 isstored, for example, in a database memory unit of the first informationprocessing apparatus 1020A. When the keyword extraction database 1030 isprovided in the first information processing apparatus 1020A, it ispossible to obviate the communication time lag during keywordextraction. Therefore, the keyword extraction can be performed in ashorter period. The database memory unit may be independently providedin the first information processing apparatus 1020A or may be providedin the memory unit 1251 of the first information processing apparatus1020A.

In the above description, the search engine 1040 is independentlyconnected to the communication network 1012 connected to the firstinformation processing apparatus 1020A. However, the first informationprocessing apparatus 1020A may include the search engine 1040. When thesearch engine 1040 is provided in the first information processingapparatus 1020A, it is possible to obviate the communication time lagduring information search. Therefore, the information search can beperformed in a shorter period.

(Search Result Display Screen)

Next, an example of an information search result display screenaccording to the present embodiment will be described in detail withreference to FIG. 34. FIG. 34 is an explanatory diagram showing anexample of search information display by the information processingapparatus according to the third embodiment.

A search result display screen 1050 displays keywords detected during avoice chat on a display screen in an updated manner. On the displayscreen, newer keywords are placed on the upper part, and older keywordsare placed on the lower part. The maximum number of keywords displayableon one screen can appropriately be set. When the number of keywordsexceeds the maximum, the lowermost keyword on the screen is deletedfirst.

In the example of FIG. 34, keywords are displayed in column 1503 with anindex number in column 1501 that is assigned in order of theirregistration time. Newer keywords, i.e., the keywords in column, 1503having greater index number in column 1501 are displayed on the upperpart. Besides the index number column 1501 and the keyword column 1503,the display screen includes a pin lock checkbox column 1505 and a deletecheckbox column 1507. The pin lock checkbox and the delete checkbox areprovided to the respective keywords. The pin lock checkbox is used tolock the keywords so that the locked keywords remain on the screen. Thedelete checkbox is used to select the keywords to be deleted when thedisplayed contents are updated.

The keywords in column 1503 are linked to their search result displayscreens showing the search result when the keywords in column 1503 aresearched using the search engine 1040. When the keywords in column 1503are clicked using a mouse pointer, for example, users can see the searchresult for the keywords by the search engine 1040.

If the pin lock checkbox in column 1505 is checked, the keyword of whichthe pin lock checkbox is checked is moved to the uppermost part andlocked. Thus, even when new keywords are displayed on the screen, thelocked keyword is not moved down. If there are plural locked keywords,they may be displayed in order of their registration time.

Among the registered keywords extracted from the dialog of theconversation during the voice chat, there may be one that is of no useto the user of the information processing apparatus in the voice chat.In such a case, by checking the delete checkbox in column 1507 besidethe corresponding keyword, the keyword can be deleted when the displayedcontents are updated.

Regarding one keyword in column 1503, not only the representation of thekeyword but also the articles related to the keyword in column 1503described in the search engine 1040 are displayed, for example, inthumbnails in column 1509 below the corresponding keyword in column1503. The articles in column 1509 related to the keyword are linked tothe full-text of the articles described in the search engine 1040 whenusers click on the articles in column 1509 using a mouse pointer, forexample. The pin lock checkbox in column 1505 and the delete checkbox incolumn 1507 are also provided to the respective articles in column 1509.The number of articles related to the keyword in column 1503 displayablein column 1509 is not limited to that illustrated in the drawing but canbe set arbitrarily. The articles displayed in column 1509 of the searchresult display screen 1050 may be one that is frequently referenced inthe search engine 1040.

In the example of the display screen 1050 shown in FIG. 34, keywords,

(personal name, uttered as Cassim),

(representative, uttered as daihyou),

(country name, Yemen),”

(place name, Chiba),

(uttered as boku),” are extracted in this order during a voice chat.Since the pin lock checkbox of the keyword,

(personal name, uttered as Cassim),” is checked, although it is theoldest keyword of the registered keywords, it is displayed on theuppermost part of the display screen 1050. The delete checkboxes of thekeyword

(representative, uttered as daihyou)” and the information

(Niigata City Council of Social Welfare Homepage)” related to thekeyword

(uttered as boku)” are checked. Therefore, such a keyword andkeyword-related information is deleted when the displayed contents areupdated.

Regarding the keywords displayed in column 1503 of the display screen1050, the same keywords are displayed substantially simultaneously onthe screens of the information processing apparatuses 1020 of therespective speakers in the voice chat by the keyword synchronizationunit 1245 installed in the information processing apparatuses 1020.However, since the checking of the pin lock checkbox and the deletecheckbox is independently operated by the respective speakers, differentcontents may be displayed on the respective display screens 105 of theinformation processing apparatuses 1020 with the progress of the voicechat.

(Reference History Data of Search Information)

Next, a method of using a reference history of the search informationduring keyword extraction according to the present embodiment will bedescribed with reference to FIG. 35. FIG. 35 is an explanatory diagramshowing reference history data of the search information according tothe third embodiment.

In the information processing apparatus 1020 according to the presentembodiment, the keywords in column 1503 selected by the user of theinformation processing apparatus 1020 on the search result displayscreen 1050 are stored as reference history data in the referencehistory memory unit 1255 in a correlated manner with information asshown in FIG. 35, for example.

As shown in FIG. 35, the reference history data includes a keyword incolumn 1601 selected by the user, weight information in column 1603representing the number of selections of the keyword in column 1601,session ID information in column 1605, which is an identifier foridentifying a voice chat in which the keyword in column 1601 isselected, and conversational counterpart information in column 1607representing a counterpart in each voice chat to which is assigned thesession ID.

The weight information in column 1603 is information representing thenumber of selections of the keyword in column 1601 in the voice chatsystem 1010 of the present embodiment. In the reference historyinformation shown in FIG. 35, a keyword,

(Japan Cup)”, is totally selected twice; and keywords,

” and

are selected once, respectively.

In the voice chat system according to the present embodiment, whenever avoice chat is performed, a session ID in column 1605 including the dataof the voice chat and a session number of the voice chat during the dateis assigned to each voice chat session. In the reference history datashown in FIG. 35, the keyword,

(Japan Cup),” is selected twice: once in a voice chat of a session ID“200609150001”; and once in a voice chat of a session ID “200609150002.”

The conversational counterpart information in column 1607 is datarepresenting a counterpart of a voice chat in which the keyword incolumn 1601 is selected. In the reference history data shown in FIG. 35,the keyword,

(Japan Cup),” is selected twice by two participants: once by aparticipant “A” in a voice chat of a session ID “200609150001”; and onceby a participant “B” in a voice chat of a session ID “200609150002.”

In the information processing apparatus 1020 according to the presentembodiment, such reference history data can be used in extraction ofkeywords from the voice data. By using the reference history data, it ispossible to acquire information such as directivity of theconversational counterpart on a topic or relatedness between words. Withsuch information, the speech recognition or the keyword extraction canbe performed more efficiently. Hereinafter, the way the referencehistory information is used will be described briefly.

The keyword extraction unit 1237 according to the present embodiment canreference the reference history memory unit 1255, in which theabove-described reference history data is stored, when performing speechrecognition, to use a variety of information contained in the referencehistory data as one of the parameter information used in the speechrecognition. For example, when performing speech recognition, thekeyword extraction unit 1237 can increase the speech recognitionpriority of a keyword having a greater number in the weight informationcolumn 1603 of the reference history data by referencing the referencehistory memory unit 1255. Accordingly, the speech recognition can beperformed efficiently.

When a keyword recognized by the keyword extraction unit 1237 isregistered in the reference history data, the speech recognitionpriority of another keyword selected in a chat session having the samesession ID as the registered keyword can be increased. This is becauseit is predicted that the keywords having the same session ID have strongare strongly related to each other.

When a keyword recognized by the keyword extraction unit 1237 isregistered in the reference history data, the speech recognitionpriority of another keyword selected by the same conversationalcounterpart as the registered keyword can be increased. This is becauseit is predicted that the keywords selected during the voice chat by thesame conversational counterpart are coincident with each other in termsof the directivity of the conversational counterpart on a topic.

As described above, according to the information processing apparatus1020 of the present embodiment, by effectively feeding back thereference history data, it becomes possible to perform the speechrecognition and the keyword extraction more efficiently.

Modified Example of Information Processing Apparatus

Next, a modified example of the information processing apparatus 1020according to the present embodiment will be described briefly withreference to FIGS. 36A to 36D. FIG. 36A is a simplified block diagramfor explaining a speech recognition method of the information processingapparatus according to the third embodiment. FIGS. 36B to 36D aresimplified block diagrams for explaining modified examples of the speechrecognition method of the information processing apparatus according tothe third embodiment.

In the information processing apparatuses 1020A and 1020B shown in FIGS.36A to 36D, only some of the processing units of the respectiveinformation processing apparatuses are illustrated. Needless to say, inaddition to the processing units illustrated, processing unitsillustrated in FIG. 31 are also included in the information processingapparatuses.

In the information processing apparatus 1020 according to the presentembodiment, as shown in FIG. 36A, it has been described for the case inwhich the first and second information processing apparatuses 1020A and1020B performing a voice chat receive sounds uttered by thecorresponding users to cause the speech recognition unit 1233 to performspeech recognition and cause the keyword synchronization unit 1245 toperform a keyword synchronization process. However, the informationprocessing apparatus of the present embodiment may be modified in thefollowing manner.

First Modified Example

A first modified example of FIG. 36B shows the case in which theinformation processing apparatuses 1020A and 1020B performing a voicechat transmit sounds uttered by the corresponding users as it is totheir counterpart information processing apparatuses and perform speechrecognition on the received sounds uttered by the users of thecounterpart information processing apparatuses.

Specifically, the sounds uttered by the user of the first informationprocessing apparatus 1020A are transmitted as it is to the secondinformation processing apparatus 1020B via the voice conversationcontrol unit 1239 and the communication unit 1249 and speech-recognizedby the second information processing apparatus 1020B. Likewise, thesounds uttered by the user of the second information processingapparatus 1020B are transmitted as it is to the first informationprocessing apparatus 1020A via the voice conversation control unit 1239and the communication unit 1249 and speech-recognized by the firstinformation processing apparatus 1020A. In the present modified example,the speech recognition, the keyword extraction, and the keyword-relatedinformation search are performed in both the first and secondinformation processing apparatuses 1020A and 1020B.

Second Modified Example

A second modified example of FIG. 36C shows the case in which the speechrecognition is performed in only one of the information processingapparatuses and the keyword synchronization and the information searchare performed in the other information processing apparatus.Specifically, the speech recognition is performed in the firstinformation processing apparatus 1020A, and the keyword synchronizationprocess is performed in the second information processing apparatus1020B. The sounds uttered by the user of the first informationprocessing apparatus 1020A are speech-recognized and keyword-extractedby the speech recognition unit 1233 and are then transmitted to thesecond information processing apparatus 1020B. Then, the secondinformation processing apparatus 1020B performs the keywordsynchronization process and the search of the keyword-relatedinformation. The sounds uttered by the user of the second informationprocessing apparatus 1020B are transmitted as it is to the firstinformation processing apparatus 1020A and are then speech-recognizedand keyword-extracted by the speech recognition unit 1257.

In the example of FIG. 36C, the speech recognition is performedindependently in the first information processing apparatus 1020A.However, the speech recognition may be performed independently in thesecond information processing apparatus 1020B. In the example of FIG.36C, two independent speech recognition units are provided in the firstinformation processing apparatus 1020A. However, the above-describedspeech recognition may be performed by only one speech recognition unit.The present modified example is useful when the processing capability ofone information processing apparatus is far superior to the otherinformation processing apparatus, and vice-versa.

Third Modified Example

A third modified example of FIG. 36D shows the case in which the speechrecognition is rarely performed in the information processingapparatuses but in the server 1016 that relays the connection betweenthe information processing apparatuses, and the apparatuses perform onlythe keyword synchronization and the information search. Specifically,the sounds uttered by the user of the first information processingapparatus 1020A are transmitted as it is to the server 1016 and arespeech-recognized by the speech recognition unit 1163 of the server 1016to be transmitted to the second information processing apparatus 1020B.Meanwhile, the sounds uttered by the user of the second informationprocessing apparatus 1020B are transmitted as it is to the server 1016and are speech-recognized by the speech recognition unit 1163 of theserver 1016 to be transmitted to the first information processingapparatus 1020A. In the example of FIG. 36D, two independent speechrecognition units are provided in the server 1016. However, theabove-described speech recognition may be performed by only one speechrecognition unit.

Fourth Embodiment

Hereinafter, a keyword extraction system according to a fourthembodiment of the present invention will be described in detail.

FIG. 37 is an explanatory diagram showing the configuration of a keywordextraction system according to the fourth embodiment of the presentinvention. As shown in FIG. 37, the keyword extraction system 1011according to the present embodiment includes a communication network1012, a keyword extraction database 1030, a search engine 1040, andinformation processing apparatuses 1020A and 1020B (hereinafter,sometimes, collectively referred to as information processing apparatusor apparatuses 1020). The information processing apparatus 1020A isconnected to an external display device 1070 within a home network 1018.The information processing apparatuses 1020A and 1020B and the externaldisplay device 1070 can receive broadcast information transmitted from abroadcasting station 1080.

The communication network 1012, the keyword extraction database 1030,and the search engine 1040 have the same configuration and providessubstantially the same effect as communication network 1012, the keywordextraction database 1030, and the search engine 1040 according to thethird embodiment, and detailed descriptions thereof will be omitted.

The information processing apparatus 1020 performs a chat (a voice chat)by means of voice with another information processing apparatus 1020connected thereto via the communication network 1012. The informationprocessing apparatus 1020 can request the search engine 1040 connectedthereto via the communication network 1012 to perform referencing of adatabase or search of information via the communication network 1012.

The another information processing apparatus 1020 performing the voicechat may be connected to the information processing apparatus 1020 viathe communication network 1012, as shown in the drawing. Alternatively,the another information processing apparatus 1020 may be directlyconnected to the information processing apparatus 1020, not via thecommunication network 1012, to a USB port, an IEEE 1394 port such asi.Link, an SCSI port, an RS-232C port, and the like.

The information processing apparatus 1020 is connected to the externaldisplay device 1070 described later within the home network 1018;therefore a variety of data can be communicated between the informationprocessing apparatus 1020 and the external display device 1070. Theconnection between the information processing apparatus 1020 and theexternal display device 1070 may be performed via a connection port suchas HDMI-CEC (high-definition multimedia interface-consumer electronicscontrol). The information processing apparatus 1020 can receive abroadcast wave containing the broadcast information transmitted from thebroadcasting station 1080 described later using a receiving functionprovided therein.

In the shown example shown in the drawing, the information processingapparatus 1020 is a desktop PC; however, in the present embodiment, theinformation processing apparatus 1020 may be a notebook PC.

In the present embodiment, the information processing apparatus 1020 isnot limited to the example described above but may be constructed, forexample, by a television set-top checkbox, an information appliance suchas a home-use game machine, a mobile phone, a PDA, and the like as longas it is a device capable of having a function of communicating via anetwork. Additionally or alternatively, the information processingapparatus 1020 may be a portable device, such as a portable gamemachine, a PHS, or a portable video/audio player, which is carried by auser who leased it.

The external display device 1070 is a display unit, such as a CRTdisplay unit, a liquid crystal display unit, a plasma display panelunit, or an electro-luminescence (EL) display unit. The external displaydevice 1070 receives the broadcast wave containing the broadcastinformation transmitted from the broadcasting station 1080 describedlater and displays the content of the broadcast information on a displayarea of the display unit. Here, the broadcast information transmittedfrom the broadcasting station refers to data such as broadcast textinformation, broadcast audio information, or video information, providedthrough a terrestrial digital broadcasting such as a one-segment digitalbroadcasting or a 12-segment digital broadcasting (hereinafter, referredto as full-segment digital broadcasting), a cable broadcasting, or anInternet broadcasting via a network. The broadcast wave containing thebroadcast information refers to a wave of the terrestrial digitalbroadcasting such as the one-segment digital broadcasting or thefull-segment digital broadcasting. The external display device 1070 cantransmit the received broadcast information to the informationprocessing apparatus 1020 via a connection port such as HDMI-CEC. Theexternal display device 1070 can receive a variety of data transmittedfrom the information processing apparatus 1020 and display informationcorresponding to the data.

Hereinafter, the fourth embodiment will be described by way of theexample of the terrestrial digital broadcasting.

The broadcasting station 1080 transmits a broadcast wave containingbroadcast information composed of data including: broadcast textinformation, broadcast audio information, and video information. Theexternal display device 1070 receives the broadcast wave transmittedfrom the broadcasting station 1080 and displays caption information oroutputs a sound based on the broadcast text information contained in thebroadcast wave. The information processing apparatus 1020 can receivethe broadcast wave transmitted from the broadcasting station 1080 to usethe content of the broadcast wave in a variety of processing.

(Configuration of Information Processing Apparatus 1020)

Next, the configuration of the information processing apparatus 1020according to the present embodiment will be described in detail. Thehardware configuration of the information processing apparatus 1020according to the present embodiment is substantially the same as thehardware configuration according to the third embodiment, and detaileddescriptions thereof will be omitted.

FIG. 38 is a block diagram for explaining the configuration of theinformation processing apparatus 1020 according to the fourthembodiment. As shown in FIG. 38, the information processing apparatus1020 according to the present embodiment includes a keywordsynchronization unit 1245, a display unit 1247, a communication unit1249, a memory unit 1251, a broadcast text information receiving unit1261, a keyword extraction unit 1263, an information search unit 1265,and an external display device connection control unit 1267.

The keyword synchronization unit 1245 transmits the keywords extractedby the keyword extraction unit 1237 from the voice data to the otherinformation processing apparatus 1020 via the communication unit 1249,thereby synchronizing the first and second information processingapparatuses 1020A and 1020B. The keyword synchronization process can beperformed not only in the direction from the information processingapparatus 1020 to another information processing apparatus 1020, butalso from the another information processing apparatus 1020 to theinformation processing apparatus 1020 in the following manner. That is,the information processing apparatus 1020 may response to the keywordsynchronization process initiated by the another information processingapparatus 1020 so that the keywords transmitted from the anotherinformation processing apparatus 1020 are received to the informationprocessing apparatus 1020.

The display unit 1247 displays the information search result transmittedfrom the information search unit 1265 to an output device such as adisplay or the like provided to the information processing apparatus1020 via a browser application, for example. The information that theinformation search unit 1265 acquires from the search engine 1040contains a URL or the like of the information or articles in the searchengine 1040. Therefore, when the user of the information processingapparatus 1020 selects the displayed information by means of an inputdevice such as a mouse or a keyboard connected to the informationprocessing apparatus 1020, the display unit 1247 requests theinformation search unit 1265 to acquire the details of the selectedinformation.

The communication unit 1249 is a communication device installed in theinformation processing apparatus 1020, for example. The communicationunit 1249 relays communication of information via the communicationnetwork 1012 between the information processing apparatus 1020,specifically, the information search unit 1265, the keyword extractionunit 1263, and the keyword synchronization unit 1245 of the informationprocessing apparatus 1020, and the external device of the informationprocessing apparatus 1020, specifically the keyword extraction database1030, the search engine 1040 or another information processing apparatus1020.

Moreover, the communication unit 1249 can communicate information withother information processing apparatus that are directly connected tothe information processing apparatus 1020 not via the communicationnetwork 1012.

The memory unit 1251 is a storage device installed in the informationprocessing apparatus 1020, for example, and stores therein data such asthe keywords extracted by the keyword extraction unit 1263 or the searchinformation acquired by the information search unit 1265. Besides thesedata, the memory unit 1251 can store therein a variety of databases.Furthermore, the memory unit 1251 may further appropriately storetherein a variety of parameters that need be stored when the informationprocessing apparatus 1020 performs a process and progress information ofthe process. The memory unit 1251 is accessible when the informationsearch unit 1265, the keyword synchronization unit 1245, or the likefreely performs reading or writing to the memory unit 1251. The memoryunit 1251 further includes a search information accumulation unit 1253and a reference history memory unit 1255.

The search information accumulation unit 1253 accumulates the searchinformation acquired by the information search unit 1265 and theinformation acquisition data in a correlated manner. When it is desiredto display once-acquired search information, the information stored inthe search information accumulation unit 1253 can be referenced todisplay the once-acquired search information.

The reference history memory unit 1255 stores, as a reference history,the keywords that the user of the information processing apparatus 1020has referenced among the keywords or articles displayed on the displayunit 1247 for more detailed information. The reference history is datathat includes the referenced keywords, weight information of thereferenced keywords, an identifier of the voice chat itself havingreferenced the keywords, and a counterpart of the voice chat. Thereference history stored in the reference history memory unit 1255 maybe used when the keyword extraction unit 1263 extracts the keywords.

The information search unit 1265, the keyword synchronization unit 1245,and the display unit 1247 may be constructed by a specialized hardwarethat is specialized to the respective function and may be provided as anapplication program such as a speech recognition program.

The broadcast text information receiving unit 1261 acquires, from theexternal display device 1070, reception channel information concerning abroadcast channel through which the external display device 1070 iscurrently receiving. Here, the reception channel information refers toinformation that represents a broadcast channel through which theexternal display device 1070 is currently receiving. The broadcast textinformation receiving unit 1261 can synchronize the reception broadcastchannel of the broadcast text information receiving unit 1261 with thereception broadcast channel of the external display device 1070 byacquiring the reception channel information from the external displaydevice 1070.

The broadcast text information receiving unit 1261 receives a broadcastwave corresponding to the reception broadcast channel of the externaldisplay device 1070 directly from the broadcasting station 1080 based onthe acquired reception channel information. At this time, the broadcasttext information receiving unit 1261 may be configured to directlyreceive an one-segment broadcast wave among the broadcast wavetransmitted from the broadcasting station 1080 and acquires textinformation from the received wave. The broadcast text informationreceiving unit 1261 may be configured to directly receive thefull-segment broadcast wave transmitted from the broadcasting station1080.

The broadcast text information receiving unit 1261 may be configured toreceive the broadcast text information received by the external displaydevice 1070 and transmitted to the information processing apparatus 1020from the external display device 1070 based on the acquired receptionchannel information.

The broadcast text information receiving unit 1261 outputs the receivedbroadcast text information to the keyword extraction unit 1263 describedlater. The broadcast text information receiving unit 1261 may record thereceived broadcast text information in the memory unit 1251.

The keyword extraction unit 1263 extracts keywords from the characterstring contained in the broadcast text information received by thebroadcast text information receiving unit 1261 based on the keywordextraction database 1030.

When the keyword extraction unit 1263 extracts the keywords, the keywordextraction unit 1263 can reference the keyword extraction database 1030connected to the communication network 1012 via the communication unit1249.

A plurality of keywords are contained in the character string thatrepresents the broadcast text information. The keyword extraction unit1263 automatically extracts all the keywords existing in the characterstring. The keyword extraction unit 1263 transmits the extractedkeywords to the information search unit 1265 and the external displaydevice control unit 1267, which will be described later. The keywordextraction unit 1263 may store the extracted keywords in the memory unit1251.

The information search unit 1265 stores, in the memory unit 1251, thekeywords transmitted from the keyword extraction unit 1263 and the timeat which the keywords were transmitted from the keyword extraction unit1263 in a correlated manner. The information search unit 1265 determineswhether or not a keyword synchronization process is to be performed onthe keywords transmitted from the keyword extraction unit 1263. When itis determined that the keyword synchronization process should beperformed, the information search unit 1265 transmits the keywords tothe keyword synchronization unit 1245, thereby requesting the executionof the keyword synchronization process. The information search unit 1265accesses the search engine 1040 via the communication unit 1249 andperforms information search of the keywords transmitted from the keywordextraction unit 1263, thereby acquiring a search result for the keywordsand the articles related to the keywords. The information search unit1265 stores the obtained search result in the search result storage unit1253 of the memory unit 1251 and transmits the search result to thedisplay unit 1247 and the external display device connection controlunit 1267 described later. Here, the search result that the informationsearch unit 1265 acquires from the search engine 1040 includes a titleor an URL of information about the search keyword in the search engine1040 and a metadata of information, such as a genre of the information.

When requested by the display unit 1247 or the external display deviceconnection control unit 1267 to acquire more detailed information abouta specific keyword or an article related to the keyword, the informationsearch unit 1265 accesses the search engine 1040 via the communicationunit 1249 to acquire the more detailed information and stores thespecific keyword notified from the display unit 1247 or the externaldisplay device connection control unit 1267 in the reference historymemory unit 1255 of the memory unit 1251.

The external display device connection control unit 1267 performsconnection control between the information processing apparatus 1020 andthe external display device 1070 connected to the information processingapparatus 1020. The external display device connection control unit 1267transmits the keywords extracted by the keyword extraction unit 1263 andthe search result for the keywords acquired by the information searchunit 1265 to the external display device 1070. When requested by theexternal display device 1070 to acquire more detailed information abouta specific keyword or an article related to the keyword, the externaldisplay device connection control unit 1267 may transmit the request tothe information search unit 1265. When the information search unit 1265acquires more detailed information from the search engine 1040 or thelike in response to the request, the external display device connectioncontrol unit 1267 outputs the detailed information acquired by theinformation search unit 1265 to the external display device 1070.Incidentally, when transmitting data corresponding to a variety ofinformation to the external display device 1070, the external displaydevice connection control unit 1267 may transform a format of the datato be transmitted into a format that can be displayed by the externaldisplay device 1070.

The external display device connection control unit 1267 may transmit,to the search engine 1040, information on the selected keywords based onthe content recorded in the reference history memory unit 1255. Thesearch engine 1040 can use the information transmitted from the externaldisplay device connection control unit 1267 in a variety of processingexecuted within the search engine 1040.

Hereinabove, an example of the function of the information processingapparatus 1020 according to the present embodiment has been described.The components described above may be constructed using ageneral-purpose element or circuit or may be constructed by aspecialized hardware that is specialized to the functions of therespective components. The whole functions of the components may beexecuted by a CPU or the like. Therefore, the hardware configuration canbe appropriately modified in accordance with the level of technology atthe time of practicing the present embodiment.

The information processing apparatus 1020 according to the presentembodiment may further include the speech recognition unit or the voiceconversation control unit of the information processing apparatus 1020according to the third embodiment. The information processing apparatus1020 may further include a database memory unit that stores the contentof the keyword extraction database 1030. With this, the content of thekeyword extraction database 1030 can be stored in the database memoryunit provided in the information processing apparatus 1020. Therefore,it is possible to shorten the time necessary for the informationprocessing apparatus 1020 to access the keyword extraction database1030. As a result, it is possible to shorten the time necessary for theinformation processing apparatus 1020 to perform the keyword extraction.In addition, by updating the content of the database memory unit on aperiodic basis, the information processing apparatus 1020 can acquirethe content of the updated database recorded in the keyword extractiondatabase 1030.

(Configuration of External Display Device 1070)

Next, the configuration of the external display device 1070 according tothe present embodiment will be described in detail with reference toFIGS. 39 and 40. FIG. 39 is a block diagram for explaining theconfiguration of an external display device according to the fourthembodiment. FIG. 40 is an explanatory diagram showing an informationdisplay screen of the external display device according to the secondembodiment.

The hardware of the external display device 1070 according to thepresent embodiment includes a display element such as a CRT, a liquidcrystal display panel, a plasma display panel, or an EL panel, and adrive control circuit that is constructed by CPU, ROM, and RAM and usedin controlling the driving of the display element.

As shown in FIG. 39, the external display device 1070 of the presentembodiment includes a broadcast receiving unit 1701, a connection portcontrol unit 1703, a broadcast information display control unit 1705, akeyword information display control unit 1707, and a display unit 1709.

The broadcast receiving unit 1701 receives a broadcast wave transmittedfrom the broadcasting station 1080 and outputs data such as broadcasttext information, broadcast audio information, or video information,contained in the broadcast wave to the connection port control unit 1703and the broadcast information display control unit 1705, which will bedescribed later. The broadcast receiving unit 1701 may be configured torecord the received information in a memory unit (not shown) provided inthe external display device 1070 or an externally attached memory unit(not shown) connected to the external display device 1070.

The connection port control unit 1703 controls a connection port such asHDMI-CEC capable of digital communication with the informationprocessing apparatus 1020. The connection port control unit 1703transmits the reception channel information about the broadcast channel,through which the broadcast receiving unit 1701 is receiving, to theinformation processing apparatus 1020 via the connection port such asMDMI-CEC. The data received by the broadcast receiving unit 1701, suchas broadcast text information, broadcast audio information, and videoinformation, may be output to the information processing apparatus 1020via the connection port control unit 1703. The variety of datatransmitted from the information processing apparatus 1020 are input tothe external display device 1070 via the connection port control unit1703. The variety of data transmitted from the information processingapparatus 1020 are transmitted to the keyword information displaycontrol unit 1707 described later.

The broadcast information display control unit 1705 performs displaycontrol when displaying the broadcast text information, the broadcastaudio information, and the video information transmitted from thebroadcast receiving unit 1701 on the display unit 1709 described later.

The keyword information display control unit 1707 performs displaycontrol when displaying the keyword information transmitted from theinformation processing apparatus 1020 on the display unit 1709 describedlater. Here, the keyword information transmitted from the informationprocessing apparatus 1020 refers to information that includes thekeywords extracted by the information processing apparatus 1020, asearch result for the extracted keywords, and the articles related tothe keywords. Upon receiving, from the display unit 1709, a request foracquisition of detailed information on the information selected by theuser of the external display device 1070 selecting the informationdisplayed on the display unit 1709 by means of an input device such as amouse, a keyboard, or a remote controller, the keyword informationdisplay control unit 1707 transmits the detailed information acquisitionrequest to the information processing apparatus 1020 via the connectionport control unit 1703.

The display unit 1709 displays, on an information display screen of theexternal display device 1070, the broadcast text information, thebroadcast audio information, and the video information, which aredisplay-controlled by the broadcast information display control unit1705, and the keyword information, which is display-controlled by thekeyword information display control unit 1707.

The information display screen 1751 of the external display device 1070normally includes an image display area 1753 on which the broadcast textinformation, the broadcast audio information, and the video informationare displayed. Here, when the keyword information is transmitted fromthe information processing apparatus 1020, the display area of theinformation display screen 1751 is divided to generate a keywordinformation display area 1755 on which the keyword information isdisplayed. The image display area 1753 is controlled, for example, bythe broadcast information display control unit 1705, and the keywordinformation display area 1755 is controlled, for example, by the keywordinformation display control unit 1707.

The details of the keyword information display area 1755 aresubstantially the same as the search result display screen 1050 of theinformation processing apparatus according to the third embodiment ofthe present invention, and detailed descriptions thereof will beomitted.

Hereinabove, an example of the function of the external display device1070 according to the present invention has been described. Thecomponents described above may be constructed using a general-purposeelement or circuit or may be constructed by a specialized hardware thatis specialized to the functions of the respective components. The wholefunctions of the components may be executed by a CPU or the like.Therefore, the hardware configuration can be appropriately modified inaccordance with the level of technology at the time of practicing thepresent embodiment.

(Keyword Extraction Method)

Next, an example of a keyword extraction method performed by theinformation processing apparatus 1020 according to the presentembodiment will be described in detail with reference to FIG. 41. FIG.41 is a flowchart for explaining a keyword extraction method accordingto the fourth embodiment.

First, the broadcast text information receiving unit 1261 of theinformation processing apparatus 1020 receives broadcast textinformation from the external display device 1070 or the broadcastingstation 1080 based on the reception channel information acquired fromthe external display device 1070, thereby acquiring the character stringof the broadcast caption as text information data (Step S1301). Thebroadcast text information receiving unit 1261 outputs the acquired textinformation data to the keyword extraction unit 1263.

Next, the keyword extraction unit 1263 applies morphological analysis tothe transmitted text information data to extract words from thecharacter string and records the extracted words on a memory of theinformation processing apparatus 1020 (Step S1303).

Next, the keyword extraction unit 1263 searches for the extracted wordsusing the information of the keyword extraction database 1030 connectedto the communication network 1012 or the content of the keywordextraction database 1030 (Step S1305).

Subsequently, the keyword extraction unit 1263 determines whether or notthe extracted words exist in the keyword extraction database 1030 (StepS1307). When the extracted words exist in the keyword extractiondatabase 1030, the keyword extraction unit 1263 records the existingextracted words on the memory as broadcast keyword data (Step S1309).When the extracted words do not exist in the keyword extraction database1030, the keyword extraction unit 1263 performs a process of Step S1311described later.

Next, the keyword extraction unit 1263 determines whether or not theextracted words, which were not found in the keyword extraction database1030, exist on the memory (Step S1311). When the unfound words exist onthe memory, the process of Step S1305 is performed. When the unfoundwords do not exist in the memory, the keyword extraction unit 1263outputs the broadcast keyword data existing on the memory as anextracted keyword (Step S1313).

By using the method described above, the information processingapparatus 1020 according to the present embodiment can extract keywordsfrom the received broadcast text information.

The keyword synchronization method executed by the informationprocessing apparatus 1020 according to the present embodiment issubstantially the same as the keyword synchronization method executed bythe information processing apparatus 1020 according to the thirdembodiment of the present embodiment, and detailed descriptions thereofwill be omitted.

In the information processing apparatus 1020 according to the presentembodiment, the words (keywords) existing in the keyword extractiondatabase 1030 are automatically extracted from the broadcast textinformation transmitted from the broadcasting station 1080. Therefore,it is possible to display the extracted keywords to the external displaydevice 1070. By using such a function, the user performing bidirectionalcommunication such as a chat using the information processing apparatus1020 or the external display device 1070 can use the extracted keywordsas a topic of the chat or the like.

First Modified Example of Information Processing Apparatus according toFourth Embodiment

Next, a first modified example of the information processing apparatus1020 according to the present embodiment will be described in detailwith reference to FIGS. 42 and 43. FIG. 42 is a block diagram forexplaining the configuration of the information processing apparatus1020 according to the present modified example. FIG. 43 is a flowchartfor explaining a keyword extraction method according to the presentmodified example. The hardware configuration of the informationprocessing apparatus 1020 according to the present modified example issubstantially the same as the hardware configuration of the fourthembodiment of the present invention, and detailed descriptions thereofwill be omitted.

As shown in FIG. 42, the information processing apparatus 1020 accordingto the present modified example includes a keyword synchronization unit1245, a display unit 1247, a communication unit 1249, a memory unit1251, a broadcast audio information receiving unit 1269, an informationsearch unit 1265, an external display device connection control unit1267, a parameter extraction unit 1271, and a keyword extraction unit1273.

The keyword synchronization unit 1245, the display unit 1247, thecommunication unit 1249, the memory unit 1251, the information searchunit 1265, and the external display device connection control unit 1267according to the present modified example have substantially the sameconfiguration and provides substantially the same effect as the keywordsynchronization unit 1245, the display unit 1247, the communication unit1249, the memory unit 1251, the information search unit 1265, and theexternal display device connection control unit 1267, and detaileddescriptions thereof will be omitted.

The broadcast audio information receiving unit 1269 acquires, from theexternal display device 1070, reception channel information concerning abroadcast channel through which the external display device 1070 iscurrently receiving. The broadcast audio information receiving unit 1269can synchronize the reception broadcast channel of the broadcast audioinformation receiving unit 1269 with the reception broadcast channel ofthe external display device 1070 by acquiring the reception channelinformation from the external display device 1070.

The broadcast audio information receiving unit 1269 receives a broadcastwave corresponding to the reception broadcast channel of the externaldisplay device 1070 directly from the broadcast 1080 based on theacquired reception channel information. At this time, the broadcastaudio information receiving unit 1269 may directly receive anone-segment broadcast wave among the broadcast wave transmitted from thebroadcasting station 1080 and acquire audio information from thereceived wave. The broadcast audio information receiving unit 1269 maybe configured to directly receive the full-segment broadcast wavetransmitted from the broadcasting station 1080.

The broadcast audio information receiving unit 1269 may be configured toreceive the broadcast audio information received by the external displaydevice 1070 and transmitted to the information processing apparatus 1020from the external display device 1070 based on the acquired receptionchannel information.

The broadcast audio information receiving unit 1269 outputs the receivedbroadcast audio information to the keyword extraction unit 1271. Thebroadcast audio information receiving unit 1269 may record the receivedbroadcast audio information in the memory unit 1251.

The parameter extraction unit 1271 and the keyword extraction unit 1273are processing units of the speech recognition unit 1233 of theinformation processing apparatus 1020 according to the present modifiedexample. The parameter extraction unit 1271 extracts feature parameterssuch as Mel Frequency Cepstrum Coefficients (MFCC) and time differenceparameter thereof, spectrum of the voice data, power linear predictivecoefficients, cepstrum coefficients, and a line spectrum pair, from eachframe (at appropriate time intervals) of the generated voice data.

The parameter extraction unit 1271 transmits the extracted featureparameters to the keyword extraction unit 1273. The parameter extractionunit 1273 may store, in the memory unit 1251 described later, theextracted feature parameters.

The keyword extraction unit 1273 extracts keywords from the voice datacontained in the broadcast audio information based on the keywordextraction database 1030 and the feature parameters generated andextracted by the parameter extraction unit 1271. When the keywordextraction unit 1273 extracts the keywords, the keyword extraction unit1273 can reference the keyword extraction database 1030 connected to thecommunication network 1012 via the communication unit 1249.

Typically, a plurality of keywords is contained in the voice datacontained in the broadcast audio information. The keyword extractionunit 1273 automatically extracts all the keywords existing in the voicedata. The keyword extraction unit 1273 transmits the extracted keywordsto the information search unit 1265. The keyword extraction unit 1273may store the extracted keywords in the memory unit 1251.

Hereinabove, an example of the function of the information processingapparatus 1020 according to the present modified example has beendescribed. The components described above may be constructed using ageneral-purpose element or circuit or may be constructed by aspecialized hardware that is specialized to the functions of therespective components. The whole functions of the components may beexecuted by a CPU or the like. Therefore, the hardware configuration canbe appropriately modified in accordance with the level of technology atthe time of practicing the present embodiment.

The information processing apparatus 1020 according to the presentmodified example may further include the voice conversation control unitof the information processing apparatus 1020 according to the thirdembodiment of the present invention. The information processingapparatus 1020 may further include a database memory unit that storesthe content of the keyword extraction database 1030. With this, thecontent of the keyword extraction database 1030 can be stored in thedatabase memory unit provided in the information processing apparatus1020. Therefore, it is possible to shorten the time necessary for theinformation processing apparatus 1020 to access the keyword extractiondatabase 1030. As a result, it is possible to shorten the time necessaryfor the information processing apparatus 1020 to perform the keywordextraction.

(Keyword Extraction Method)

Next, an example of a keyword extraction method performed by theinformation processing apparatus 1020 according to the present modifiedexample will be described in detail with reference to FIG. 43.

First, the broadcast audio information receiving unit 1269 of theinformation processing apparatus 1020 receives broadcast audioinformation from the external display device 1070 or the broadcastingstation 1080 based on the reception channel information acquired fromthe external display device 1070. The parameter extraction unit 1271 andthe keyword extraction unit 1273 perform speech recognition on the voicedata and determine a speech recognition result (Step S1401).

Next, the keyword extraction unit 1273 applies morphological analysis tothe speech recognition result to extract words from the speechrecognition result and records the extracted words on a memory of theinformation processing apparatus 1020 (Step S1403).

Next, the keyword extraction unit 1273 searches for the extracted wordsusing the information of the keyword extraction database 1030 connectedto the communication network 1012 or the content of the keywordextraction database 1030 (Step S1405).

Subsequently, the keyword extraction unit 1273 determines whether or notthe extracted words exist in the keyword extraction database 1030 (StepS1407). When the extracted words exist in the keyword extractiondatabase 1030, the keyword extraction unit 1273 records the existingextracted words on the memory as broadcast keyword data (Step S1409).When the extracted words do not exist in the keyword extraction database1030, the keyword extraction unit 1273 performs a process of Step S1411described later.

Next, the keyword extraction unit 1273 determines whether or not theextracted words, which were not found in the keyword extraction database1030, exist on the memory (Step S1411). When the unfound words exist onthe memory, the process of Step S1405 is performed. When the unfoundwords do not exist in the memory, the keyword extraction unit 1273outputs the broadcast keyword data existing on the memory as anextracted keyword (Step S1413).

By using the method described above, the information processingapparatus 1020 according to the present modified example can extractkeywords from the received broadcast audio information.

The keyword synchronization method executed by the informationprocessing apparatus 1020 according to the present modified example issubstantially the same as the keyword synchronization method executed bythe information processing apparatus 1020 according to the thirdembodiment of the present invention, and detailed descriptions thereofwill be omitted.

In the information processing apparatus 1020 according to the presentmodified example, the words (keywords) existing in the keywordextraction database 1030 are automatically extracted from the broadcastaudio information transmitted from the broadcasting station 1080.Therefore, it is possible to display the extracted keywords to theexternal display device 1070. By using such a function, the userperforming bidirectional communication such as a chat using theinformation processing apparatus 1020 or the external display device1070 can use the extracted keywords as a topic of the chat or the like.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the attached claims or the equivalents thereof.

For example, in the embodiments described above, the broadcastingstation 1080 transmits a terrestrial digital broadcasting. However, thebroadcasting station 1080 may provide a cable broadcasting or anInternet broadcasting.

In the embodiments described above, FIG. 38 shows the case in which thebroadcasting station 1080 provides a television program through aterrestrial digital broadcasting. However, AV contents provided by acamcorder that user can personally capture and reproduce images with.

In the embodiments described above, two information processingapparatuses perform the voice chat. However, in the voice chat systemaccording to the present embodiment, the voice chat may be performedamong plural information processing apparatuses, and the keywordsynchronization may be performed between the respective informationprocessing apparatuses.

As described above, according to the embodiment of the presentinvention, keywords related to the content of the conversation during avoice chat are automatically and efficiently synchronized. In addition,keywords contained in broadcast information are automatically andefficiently synchronized.

What is claimed is:
 1. A voice chat system, comprising: a plurality ofinformation processing apparatuses that perform a voice chat whileperforming speech recognition; and a search server connected to theplural information processing apparatuses via a communication network,wherein the search server discloses a search keyword list containing thesearch keywords searched by the search server and rank informationassociated with the search keyword list to at least one of theinformation processing apparatuses, the at least one informationprocessing apparatus comprising: a recognition word dictionarygenerating unit that acquires the search keyword list from the searchserver to generate a recognition word dictionary containing words foruse in the speech recognition; a speech recognition unit that performsspeech recognition on voice data obtained from a dialog of theconversation during the voice chat by referencing a recognition databasecontaining the recognition word dictionary; a voice conversation controlunit that performs communication control of the voice data with at leastone information processing apparatus; and a keyword detection unit thatdetects keywords related to the content of the conversation during thevoice chat from the result of the speech recognition, wherein the searchserver represents a website that provides a keyword search service and adirectory search service so that a user uses the search server to searchfor information available through Internet.
 2. An information processingapparatus acquiring, from a search server, a search keyword listcontaining the search keywords searched by the search server and rankinformation associated with the search keyword list and performing avoice chat with other information processing apparatus, the apparatuscomprising: a recognition word dictionary generating unit that acquiresthe search keyword list from the search server to generate a recognitionword dictionary containing words for use in the speech recognition; aspeech recognition unit that performs speech recognition on voice dataobtained from a dialog of the conversation during the voice chat byreferencing a recognition database containing the recognition worddictionary; a voice conversation control unit that performscommunication control of the voice data with the other informationprocessing apparatus; and a keyword detection unit that detects keywordsrelated to the content of the conversation during the voice chat fromthe result of the speech recognition, wherein the search serverrepresents a website that provides a keyword search service and adirectory search service so that a user uses the search server to searchfor information available through Internet.
 3. The informationprocessing apparatus according to claim 2, wherein the recognition worddictionary includes: a fixed word dictionary in which predeterminedwords are pre-registered; and a variable word dictionary in whichregistered words are updated on an as needed basis, and wherein therecognition word dictionary generating unit selects words to beregistered in the variable word dictionary from the search keyword listthat contains higher-rank search keywords of the search server togenerate the variable word dictionary.
 4. The information processingapparatus according to claim 3, wherein the recognition word dictionarygenerating unit determines a preference of a user of the informationprocessing apparatus based on history information of the keywordsdetected by the keyword detection unit and selects the words from thesearch keyword list based on the preference.
 5. The informationprocessing apparatus according to claim 3, wherein the recognition worddictionary generating unit searches for the words selected from thesearch keyword list using the search server and acquires a sub-keywordrelated to the words from a search result obtained by the search,thereby registering the sub-keyword in the variable word dictionary in acorrelated manner with the words.
 6. The information processingapparatus according to claim 3, wherein the recognition word dictionarygenerating unit applies a weight to the respective words selected fromthe search keyword list based on search rank information that isdetermined by a frequency of the words being searched by the searchserver.
 7. The information processing apparatus according to claim 6,wherein the recognition word dictionary generating unit calculates afrequency of the keywords based on history information of the keywordsdetected by the keyword detection unit and changes the weight of thewords registered in the variable word dictionary and corresponding tothe keywords.
 8. An information processing apparatus acquiring, from asearch server, a search keyword list containing the search keywordssearched by the search server and rank information associated with thesearch keyword list, selecting words from the search keyword list,acquiring, from a recognition word dictionary generating device thatapplies weight information for use in speech recognition to the selectedwords, the words having the weight information applied thereto, andperforming a voice chat with other information processing apparatus, theapparatus comprising: a speech recognition unit that performs speechrecognition on voice data obtained from a dialog of the conversationduring the voice chat by referencing a recognition database containingthe words acquired from the recognition word dictionary generatingdevice; a voice conversation control unit that performs communicationcontrol of the voice data with the other information processingapparatus; and a keyword detection unit that detects keywords related tothe content of the conversation during the voice chat from the result ofthe speech recognition, wherein the search server represents a websitethat provides a keyword search service and a directory search service sothat a user uses the search server to search for information availablethrough Internet.
 9. A speech recognition method used in an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server and rank information associated with the search keywordlist and performing a voice chat with other information processingapparatus, the method comprising the steps of: acquiring the searchkeyword list from the search server to generate a recognition worddictionary containing words for used in speech recognition; obtainingvoice data from the content of the conversation during the voice chat;analyzing the voice data based on an acoustic feature of the voice dataand generating word sequence candidates corresponding to the content ofthe conversation; and analyzing the generated word sequence candidatesbased on a linguistic concatenation feature between the words thatconstitute the word sequence by referencing a recognition database foruse in the speech recognition containing the recognition worddictionary, thereby selecting a most feasible word sequence, wherein thesearch server represents a website that provides a keyword searchservice and a directory search service so that a user uses the searchserver to search for information available through Internet.
 10. Aspeech recognition method used in an information processing apparatus,the apparatus acquiring, from a search server, a search keyword listcontaining the search keywords searched by the search server and rankinformation associated with the search keyword list, selecting wordsfrom the search keyword list, acquiring, from a recognition worddictionary generating device that applies weight information for use inspeech recognition to the selected words, the words having the weightinformation applied thereto, and performing a voice chat with otherinformation processing apparatus, the method comprising the steps of:acquiring the words having the weight information applied thereto fromthe recognition word dictionary generating device and storing the wordsin a recognition database for use in speech recognition; obtaining voicedata from the content of the conversation during the voice chat;analyzing the voice data based on an acoustic feature of the voice dataand generating word sequence candidates corresponding to the content ofthe conversation; and analyzing the generated word sequence candidatesbased on a linguistic concatenation feature between the words thatconstitute the word sequence by referencing the recognition database,thereby selecting a most feasible word sequence, wherein the searchserver represents a website that provides a keyword search service and adirectory search service so that a user uses the search server to searchfor information available through Internet.
 11. A non-transitory storagemedium storing a program for a computer that controls an informationprocessing apparatus, the apparatus acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server and rank information associated with the search keywordlist and performing a voice chat with other information processingapparatus, the program allowing the computer to execute: a recognitionword dictionary generating function that acquires the search keywordlist from the search server to generate a recognition word dictionarycontaining words for use in the speech recognition; a speech recognitionfunction that performs speech recognition on voice data obtained from adialog of the conversation during the voice chat by referencing arecognition database containing the recognition word dictionary; a voiceconversation control function that performs communication control of thevoice data with the other information processing apparatus; and akeyword detection function that detects keywords related to the contentof the conversation during the voice chat from the result of the speechrecognition, wherein the search server represents a website thatprovides a keyword search service and a directory search service so thata user uses the search server to search for information availablethrough Internet.
 12. A non-transitory storage medium storing a programfor a computer that controls an information processing apparatus, theapparatus acquiring, from a search server, a search keyword listcontaining the search keywords searched by the search server and rankinformation associated with the search keyword list, selecting wordsfrom the search keyword list, acquiring, from a recognition worddictionary generating device that applies weight information for use inspeech recognition to the selected words, the words having the weightinformation applied thereto, and performing a voice chat with otherinformation processing apparatus, the program allowing the computer toexecute: a speech recognition function that performs speech recognitionon voice data obtained from a dialog of the conversation during thevoice chat by referencing a recognition database containing the wordsacquired from the recognition word dictionary generating device; a voiceconversation control function that performs communication control of thevoice data with the other information processing apparatus; and akeyword detection function that detects keywords related to the contentof the conversation during the voice chat from the result of the speechrecognition, wherein the search server represents a website thatprovides a keyword search service and a directory search service so thata user uses the search server to search for information availablethrough Internet.
 13. An information processing apparatus, comprising: arecognition word dictionary generating unit that acquires, from a searchserver, a search keyword list containing the search keywords searched bythe search server and rank information associated with the searchkeyword list to generate a recognition word dictionary containing wordsfor use in language recognition; a broadcast text information receivingunit that receives broadcast text information transmitted from abroadcasting station; a keyword detection unit that detectspredetermined keywords from the broadcast text information byreferencing the recognition word dictionary; and an external displaydevice connection control unit that performs connection control with anexternal display device and outputs the keywords detected from thebroadcast text information to the external display device, wherein thesearch server represents a website that provides a keyword searchservice and a directory search service so that a user uses the searchserver to search for information available through Internet.
 14. Theinformation processing apparatus according to claim 13, wherein thebroadcast text information receiving unit acquires reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving and the broadcast text informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus.
 15. The informationprocessing apparatus according to claim 13, wherein the broadcast textinformation receiving unit acquires reception channel informationconcerning a broadcast channel through which the external display deviceis receiving, from the external display device connected to theinformation processing apparatus, and acquires the broadcast textinformation corresponding to the broadcast channel from the broadcastingstation.
 16. The information processing apparatus according to claim 13,wherein the information processing apparatus stores a reference historyof the keywords in the external display device, and wherein the externaldisplay device connection control unit notifies the search engine of akeyword selected by the external display device.
 17. An informationprocessing apparatus, comprising: a recognition word dictionarygenerating unit that acquires, from a search server, a search keywordlist containing the search keywords searched by the search server andrank information associated with the search keyword list to generate arecognition word dictionary containing words for use in speechrecognition; a broadcast audio information receiving unit that receivesbroadcast audio information transmitted from a broadcasting station; aspeech recognition unit that performs speech recognition on thebroadcast audio information by referencing a recognition databasecontaining the recognition word dictionary; a keyword detection unitthat detects predetermined keywords from the result of the speechrecognition on the broadcast audio information; and an external displaydevice connection control unit that performs connection control with anexternal display device and outputs the keywords detected from thebroadcast audio information to the external display device, wherein thesearch server represents a website that provides a keyword searchservice and a directory search service so that a user uses the searchserver to search for information available through Internet.
 18. Theinformation processing apparatus according to claim 17, wherein thebroadcast audio information receiving unit acquires reception channelinformation concerning a broadcast channel through which the externaldisplay device is receiving and the broadcast audio informationcorresponding to the broadcast channel from the external display deviceconnected to the information processing apparatus.
 19. The informationprocessing apparatus according to claim 17, wherein the broadcast audioinformation receiving unit acquires reception channel informationconcerning a broadcast channel through which the external display deviceis receiving, from the external display device connected to theinformation processing apparatus, and acquires the broadcast audioinformation corresponding to the broadcast channel from the broadcastingstation.
 20. The information processing apparatus according to claim 17,wherein the information processing apparatus stores a reference historyof the keywords in the external display device, and wherein the externaldisplay device connection control unit notifies the search engine of akeyword selected by the external display device.
 21. A keyword detectionmethod, comprising the steps of: acquiring, from a search server, asearch keyword list containing the search keywords searched by thesearch server and rank information associated with the search keywordlist to generate a recognition word dictionary containing words for usein language recognition; receiving broadcast text informationtransmitted from a broadcasting station; detecting predeterminedkeywords from the broadcast text information by referencing therecognition word dictionary; and performing connection control with anexternal display device and outputting the keywords detected from thebroadcast text information to the external display device, wherein thesearch server represents a website that provides a keyword searchservice and a directory search service so that a user uses the searchserver to search for information available through Internet.
 22. Akeyword detection method, comprising the steps of: acquiring, from asearch server, a search keyword list containing the search keywordssearched by the search server and rank information associated with thesearch keyword list to generate a recognition word dictionary containingwords for use in speech recognition; receiving broadcast audioinformation transmitted from a broadcasting station; performing speechrecognition on the broadcast audio information by referencing arecognition database containing the recognition word dictionary;detecting predetermined keywords from the result of the speechrecognition on the broadcast audio information; and performingconnection control with an external display device and outputting thekeywords detected from the broadcast audio information to the externaldisplay device, wherein the search server represents a website thatprovides a keyword search service and a directory search service so thata user uses the search server to search for information availablethrough Internet.
 23. A non-transitory storage medium storing a programfor allowing a computer to realize: a recognition word dictionarygenerating function that acquires, from a search server, a searchkeyword list containing the search keywords searched by the searchserver and rank information associated with the search keyword list togenerate a recognition word dictionary containing words for use inlanguage recognition; a broadcast text information receiving functionthat receives broadcast text information transmitted from a broadcastingstation; a keyword detection function that detects predeterminedkeywords from the broadcast text information by referencing therecognition word dictionary; and an external display device connectioncontrol function that performs connection control with an externaldisplay device and outputs the keywords detected from the broadcast textinformation to the external display device, wherein the search serverrepresents a website that provides a keyword search service and adirectory search service so that a user uses the search server to searchfor information available through Internet.
 24. A non-transitory storagemedium storing a program for allowing a computer to realize: arecognition word dictionary generating function that acquires, from asearch server, a search keyword list containing the search keywordssearched by the search server and rank information associated with thesearch keyword list to generate a recognition word dictionary containingwords for use in speech recognition; a broadcast audio informationreceiving function that receives broadcast audio information transmittedfrom a broadcasting station; a speech recognition function that performsspeech recognition on the broadcast audio information by referencing arecognition database containing the recognition word dictionary; akeyword detection function that detects predetermined keywords from theresult of the speech recognition on the broadcast audio information; andan external display device connection control function that performsconnection control with an external display device and outputs thekeywords detected from the broadcast audio information to the externaldisplay device, wherein the search server represents a website thatprovides a keyword search service and a directory search service so thata user uses the search server to search for information availablethrough Internet.
 25. A voice chat system, comprising: a plurality ofinformation processing apparatuses that performs a voice chat; a keywordextraction database referenced by the information processing apparatuseswhen extracting keywords from a dialog of the conversation during thevoice chat; and a search engine used by the information processingapparatuses when searching for the keywords and articles related to thekeywords using the extracted keywords, the search engine disclosing toat least one information processing apparatus a search keyword listcontaining search keywords searched by the search engine and rankinformation associated with the search keyword list, wherein at leastone information processing apparatus includes: a parameter extractionunit that extracts a parameter from voice data generated from thedialog, the parameter characterizing the voice data; a keywordextraction unit that recognizes the generated voice data and extractsthe keywords from the voice data based on the parameter and the keywordextraction database; an information search unit that searches for theextracted keywords using the search engine and acquires a search resultfor the keywords and the articles related to the keywords; a displayunit that displays a keyword that is correlated with address informationof the search result for the keyword and an article that is correlatedwith address information of the articles related to the keywords; and akeyword synchronization unit that transmits the extracted keywords to aninformation processing apparatus, which is a counterpart of the chat,and performs keyword synchronization with the counterpart informationprocessing apparatus, wherein the search engine represents a websitethat provides a keyword search service and a directory search service sothat a user uses the search engine to search for information availablethrough Internet.
 26. An information processing apparatus performingvoice chat with other information processing apparatus, the apparatuscomprising: a parameter extraction unit that extracts a parameter fromvoice data generated from a dialog of the conversation during the voicechat, the parameter characterizing the voice data; a keyword extractionunit that recognizes the generated voice data and extracts keywords fromthe voice data based on the parameter and a keyword extraction database;an information search unit that searches for the extracted keywordsusing a search engine and acquires a search result for the keywords andarticles related to the keywords, the information search unit acquiringfrom the search engine a search keyword list containing search keywordssearched by the search engine and rank information associated with thesearch keyword list; and a search information accumulation unit thataccumulates the keywords and the articles in a correlated manner withaddress information of the search result for the keywords and addressinformation of the articles, respectively, wherein the search enginerepresents a website that provides a keyword search service and adirectory search service so that a user uses the search engine to searchfor information available through Internet.
 27. The informationprocessing apparatus according to claim 26, further comprising a keywordsynchronization unit that transmits the extracted keywords to aninformation processing apparatus, which is a counterpart of the chat,and performs keyword synchronization with the counterpart informationprocessing apparatus.
 28. The information processing apparatus accordingto claim 26, further comprising a database memory unit that stores thekeyword extraction database.
 29. The information processing apparatusaccording to claim 26, wherein the search engine is provided within theinformation processing apparatus.
 30. The information processingapparatus according to claim 26, further comprising a display unit thatdisplays a keyword that is correlated with address information of thesearch result for the keyword and an article that is correlated withaddress information of the articles related to the keywords.
 31. Theinformation processing apparatus according to claim 26, furthercomprising a reference history memory unit that stores a referencehistory of the keywords.
 32. The information processing apparatusaccording to claim 31, wherein the reference history memory unit storesthe referenced keywords in a correlated manner with an identifierassigned to the respective chat and a counterpart of the chat.
 33. Theinformation processing apparatus according to claim 31, wherein thekeyword extraction unit extracts a keyword placed at a higher rank ofthe reference history on a preferential basis.
 34. The informationprocessing apparatus according to claim 26, wherein the keywordextraction unit extracts a higher-rank search keyword of the searchengine on a preferential basis.
 35. An information processing apparatusperforming voice chat with other information processing apparatus, theat least one information processing apparatus comprising: a parameterextraction unit that extracts a parameter from voice data generated froma dialog of the conversation during the voice chat, the parametercharacterizing the voice data; a keyword extraction unit that recognizesthe generated voice data and extracts keywords from the voice data basedon the parameter and a keyword extraction database; an informationsearch unit that searches for the extracted keywords using a searchengine and acquires a search result for the keywords and articlesrelated to the keywords, the information search unit acquiring from thesearch engine a search keyword list containing search keywords searchedby the search engine and rank information associated with the searchkeyword list; and a search information accumulation unit thataccumulates the keywords and the articles in a correlated manner withaddress information of the search result for the keywords and addressinformation of the articles, respectively, wherein the informationprocessing apparatus comprises a keyword synchronization unit thatreceives the keywords transmitted from the at least one informationprocessing apparatus and performs keyword synchronization with thecorresponding information processing apparatus, wherein the searchengine represents a website that provides a keyword search service and adirectory search service so that a user uses the search engine to searchfor information available through Internet.
 36. A non-transitory storagemedium storing a program for allowing a computer to realize: a parameterextraction function that extracts a parameter from voice data generatedfrom a dialog of the conversation during the voice chat, the parametercharacterizing the voice data; a keyword extraction function thatrecognizes the generated voice data and extracts keywords from the voicedata based on the parameter and a keyword extraction database; aninformation search function that searches for the extracted keywordsusing a search engine and acquires a search result for the keywords andarticles related to the keywords, the information searching functionacquiring from the search engine a search keyword list containing searchkeywords searched by the search engine and rank information associatedwith the search keyword list; and a search information storage functionthat stores the keywords and the articles in a correlated manner withaddress information of the search result for the keywords and addressinformation of the articles, respectively, wherein the search enginerepresents a website that provides a keyword search service and adirectory search service so that a user uses the search engine to searchfor information available through Internet.
 37. A non-transitory storagemedium storing a program for allowing a computer to realize: a keywordsynchronization function that receives keywords transmitted from atleast one information processing apparatus and performs keywordsynchronization with the corresponding information processing apparatus,wherein the keywords are extracted from a speech of a user withreference to a keyword list and associated rank information provided bya search engine representing a that provides a keyword search serviceand a directory search service so that a user uses the search engine tosearch for information available through Internet.
 38. An informationprocessing apparatus, comprising: a broadcast text information receivingunit that receives broadcast text information transmitted from abroadcasting station; a keyword extraction unit that extracts keywordsfrom the broadcast text information based on a keyword extractiondatabase; an information search unit that searches for the extractedkeywords using a search engine and acquires articles related to thekeywords, the information search unit acquiring from the search engine asearch keyword list containing search keywords searched by the searchengine and rank information associated with the search keyword list; andan external display device connection control unit that performsconnection control with an external display device and outputs thekeywords, a search result for the keywords, and articles related to thekeywords to the external display device, wherein the search enginerepresents a website that provides a keyword search service and adirectory search service so that a user uses the search engine to searchfor information available through Internet.
 39. The informationprocessing apparatus according to claim 38, wherein the broadcast textinformation receiving unit acquires reception channel informationconcerning a broadcast channel through which the external display deviceis receiving and the broadcast text information corresponding to thebroadcast channel from the external display device connected to theinformation processing apparatus.
 40. The information processingapparatus according to claim 38, wherein the broadcast text informationreceiving unit acquires reception channel information concerning abroadcast channel through which the external display device isreceiving, from the external display device connected to the informationprocessing apparatus, and acquires the broadcast text informationcorresponding to the broadcast channel from the broadcasting station.41. The information processing apparatus according to claim 38, furthercomprising a reference history memory unit that stores a referencehistory of the keywords in the external display device, wherein theexternal display device connection control unit notifies the searchengine of a keyword selected by the external display device.
 42. Theinformation processing apparatus according to claim 38, furthercomprising a keyword synchronization unit that transmits the extractedkeywords to at least one information processing apparatus and performskeyword synchronization with the at least one information processingapparatus.
 43. An information processing apparatus, comprising: abroadcast audio information receiving unit that receives broadcast audioinformation transmitted from a broadcasting station; a parameterextraction unit that extracts a parameter from voice data contained inthe broadcast audio information, the parameter characterizing the voicedata; a keyword extraction unit that recognizes the voice data andextracts keywords from the voice data based on the parameter and akeyword extraction database; an information search unit that searchesfor the extracted keywords using a search engine and acquires a searchresult for the keywords and articles related to the keywords, theinformation search unit acquiring from the search engine a searchkeyword list containing search keywords searched by the search engineand rank information associated with the search keyword list; and anexternal display device connection control unit that performs connectioncontrol with an external display device and outputs the keywords, thesearch result for the keywords, and the articles related to the keywordsto the external display device, wherein the search engine represents awebsite that provides a keyword search service and a directory searchservice so that a user uses the search engine to search for informationavailable through Internet.
 44. The information processing apparatusaccording to claim 43, wherein the broadcast audio information receivingunit acquires reception channel information concerning a broadcastchannel through which the external display device is receiving and thebroadcast audio information corresponding to the broadcast channel fromthe external display device connected to the information processingapparatus.
 45. The information processing apparatus according to claim43, wherein the broadcast audio information receiving unit acquiresreception channel information concerning a broadcast channel throughwhich the external display device is receiving, from the externaldisplay device connected to the information processing apparatus, andacquires the broadcast audio information corresponding to the broadcastchannel from the broadcasting station.
 46. The information processingapparatus according to claim 43, further comprising a reference historymemory unit that stores a reference history of the keywords in theexternal display device, wherein the external display device connectioncontrol unit notifies the search engine of a keyword selected by theexternal display device.
 47. The information processing apparatusaccording to claim 43, further comprising a keyword synchronization unitthat transmits the extracted keywords to at least one informationprocessing apparatus and performs keyword synchronization with the atleast one information processing apparatus.
 48. A non-transitory storagemedium storing a program for allowing a computer to realize: a broadcasttext information receiving function that receives broadcast textinformation broadcast from a broadcasting station; a keyword extractionfunction that extracts keywords from the broadcast text informationbased on a keyword extraction database; an information search functionthat searches for the extracted keywords using a search engine andacquires a search result for the keywords and articles related to thekeywords, the information search function acquiring from the searchengine a search keyword list containing search keywords searched by thesearch engine and rank information associated with the search keywordlist; and an external display device connection control function thatperforms connection control with an external display device and outputsthe keywords, the search result for the keywords, and the articlesrelated to the keywords to the external display device, wherein thesearch engine represents a website that provides a keyword searchservice and a directory search service so that a user uses the searchengine to search for information available through Internet.
 49. Anon-transitory storage medium storing a program for allowing a computerto realize: a broadcast audio information receiving function thatreceives broadcast audio information transmitted from a broadcastingstation; a parameter extraction function that extracts a parameter fromvoice data contained in the broadcast audio information, the parametercharacterizing the voice data; a keyword extraction function thatrecognizes the voice data and extracts keywords from the voice databased on the parameter and a keyword extraction database; an informationsearch function that searches for the extracted keywords using a searchengine and acquires a search result for the keywords and articlesrelated to the keywords the information search function acquiring fromthe search engine a search keyword list containing search keywordssearched by the search engine and rank information associated with thesearch keyword list; and an external display device connection controlfunction that performs connection control with an external displaydevice and outputs the keywords, the search result for the keywords, andthe articles related to the keywords to the external display device,wherein the search engine represents a website that provides a keywordsearch service and a directory search service so that a user uses thesearch engine to search for information available through Internet.